I r3* Ik f NATIONAL LIBRARY OF MEDICINE Bethesda, Maryland *i -»* 'p,Mp2b . /? /£■* i ■ Zii ^/ . <#' < /^ *** &S& ■,<,6 Jo***'- w* Sf* s* "«- f? 4'f //&, i . - *■'.< ^^^^£*lV/L^£_^, LECTURES ON THE ADULTERATION OF FOOD AND CULINARY FOiSON; THE DETECTION OF POISON'S IN GENERAL AND OF ADULTERATIONS IN SUNDRY CHE I'ARATIONS, &.C. USED IN MEDICINE AND THE ARTS, WITH THE MEANS OF DISCOVERING THEM r AND RBLK8 FOR DETERMINING TIO PURITY OF SUBSTANCES. DELIVERED IN THE UNITED STATES MILITARY ACADEMY. Btf JAMES CUTBUSH, A. S. U. S. A Mem. .In. Phil. Soc. Corresp. Mem. Columb. Instil. SfC and acting Professor of Chemistry and Mineralogy in ttie United States .Military Academy. PRINTED BY WARD M. GAZLAY, NEWBIRGH, N. Y. 1823. 0>^\ . XA< „.~ ~v ' Southern District o/Ntiv-York, ss. HE IT REMEMBERED, that on the 31st day of May, m the47Th year of the Independence of the United States of A- irierica, James Cutbush of the said District, hath deposited r*&4his office the title of a book the right whereof he claims as Juafior affiPoroprietor, in the words following, to wit: »*«jCectHres on .the Adulteration of Food and Culinary Poi- £only»tJe-D vh CONTENTS. LECTURE L page. Water, 5 Adulteration of Wine, 18 Adulteration of Beer, 43 Adulteration, fee. of Tea, 47 Adulteration of Chocolate, 53 Spurious or Counterfeit Coffee, 56 Adulteration of Spiritous Liquors, 60 Poisonous and other Cheese, 67 LECTURE II. Pepper, 71 Pimento, 72 Cayenne Pepper, 73 Poisonous Pickles, 74 Preparation and Adulteration of-Vinegar, 76 Wood Vinegar, 83 Adulteration of Milk and Cream, 85 Nutmegs, 93 Poisonous Confectionary, 95 Poisonous Fish, 98 Poisonous Catsup, TOO Sundry Poisons and Adulterations, 100 Portable Soup, 111 White or Caseous Butter, 115 Lard and Tallow, 120 Capers, 121 Soy, 122 Vermacelli, 125 Distilled Waters, 126 Sugar, 129 Rice Flour, 134 Ginger, 135 Cinnamon and Cloves, 136 V-U I LECTURE III. Detection of Poisons, &.C. 139 Poisons, 140 Arsenic, 151 Corrosive Sublimate, 159 Preparations of Lead, 167 Preparations of Barytes, 171 Preparations of Antimony, ■j 174 Nitrate of Silver, 175 Muriate of Tin, 175 Corrosive acids, 176 Caustic Alkalies, 176 Oxalic Acid, 176 Hydrocyanic Acid, 179 Poisonous Vegetables, 152 iEriel Poisons, 188 Antidotes for Vegetable Poisons, 198 Ergot, 202 Slow Poison from the Turkey Hair, 204 Detection of Sundry Adulterations, 206 Ultramarine, 208 Indigo, 209 Antwerp Blue, 213 Prussian Blue, 213 Verditer, 214 Smalt, 212 Carmine, 215 Florentine Lake, 217 Madder Lake, 218 Rose Pink, 219 Rouge, 219 Vermillion, 220 221 223 Red Lead, Yellow Pigments, Humes' Prussiate of Copper, 225 LECTURE IV. Brown Pigments, ii Black Pigments. . 229 Purple Pigments 232 Green Pigments, 235 White Pigments, 240 Alloys of Copper, 244 Sealing Wax, 255 Copal, 256 Lao, 258 Amber, 260 Rosin, 262 Balsam of Gilleau. 263 Balsam of Copaiba?, 264 Canada Balsam, 264 Peruvian Balsam, 265 Mecca Balsam, 266 Soap, 267 Potash, Pearl Ash and Barilla, 272 Manganese, 278 Sulphur, 280 Milk of Sulphur, 282 Plumbago, 283 Indelible Ink, 286 Coral, 288 Bezoar, 290 Ambergris, 292 Dragon's Blood, 294 Tin Putty, 295 Mother of Pearl, 296 Pearl, 297 Carbonate of Magnesia, 299 Calcined Magnesia, 300 Flowers of Zinc, 301 Calamine, 302 White Precipitate of Mercury, 304 Etliiop's Mineral, 304 Turpeth Mineral, 305 Red Precipitate, perse, 306 LECTURE V Red Precipitate, 30^ Mercurial Ointment, 310 Mercury, 311 Calomel, 313 Corrosive Sublimate, 313 Gun Powder, 317 Pure Potash, 32* Solution of Pure Potash, 326 Chlorate of Potash, 327 Nitrate of Potash, 328 Sulphate of Potash, 334 Carbonate of Potash, 984 Bi-Carbonate of Potash? 336 Acetate of Potash, 336 Sulphuret of Potash, 337 Sulphite of Potash, 338 Sal Prunella, 339 Tartrate of Potash, 340 Tartrate of Potash-and-Soda,^ 340 Supertartrate of Potasli, 341 Pure Soda,, 343 Soda Water, 344 Muriate of Soda, 348 Sulphate of Soda, 350 Carbonate of Soda, 341 Bi-Carbonate of Soda, 352 Subborate of Soda, 353 Nitrate of Soda, 353 Phosphate of Soda, 354 Alum, 355 Muriate of Ammonia, 360 Carbonate of Ammonia, 361 Carbonated liquid Ammonia, 362 Water of Pure Ammonia, 36S LECTURE Vt Nitrate of Ammonia, Spirit of Hartshorn, Acetate of Ammonia, Sulphate of Zinc, • XI Acetate of Lime, 373 Acetate of Alumina, 374 Acetate of Iron, 375 Acetate of Zinc, 375 Acetate of Lead, 376 Sulphate of Zinc, 877 Sulphate of Iron, 378 Red Sulphate of Iron, 380 Proto-muriate of Iron, 382 Mnrtial Flowers, 383 Native Prussian Blue, 383 Muriate of Gold, 384 Nitrate of Silver, 385 Tartrate of Potash-and-Antimohy, 386 Muriate of Antimony, S89 Vit. Sulphuretted Oxyde of Antimony, 389 Crocus of Antimony, 391 Precipitated Sulpliuretted Oxyde df Antimony, 391 Phospiiate of Lime-and-Antimony, 392 Sulphate of Magnesia, S9fi Acid of Benzoin, S9G Acetic Acid, 396 Tartaric acid, 397 Boracic Acid, 399 Succinic Acid, S99 Sulphuric Acid, 400 Sulphureous Acid, 402 Nitric Acid, 402 Nitro-Muriatic Acid) 404 Muriatic Acid, 405 Opium, 407 Alcohol and Mther, 411 Essential Oils, 411 Olive Oil, 416 Cajeput Oil, 417 Camphor, 419 Spermaceti and Tallow, 420 Wax and Tallow, 422 White and Yellow Wax, 424 xn Hair Powder, Anatto, Turmeric, 4iy 427 428 Peruvian Bark, 429 Cochineal, 431 Spanish Liquorice, Isinglass, Glue, 432 432 434 Adulteration of Arsenic, 435 Red and Yellow Sulphuret of Arsenic, Arsenite of Potash, 437 438 White Oxyde of Bismuth, 439 Natural and Artificial Gems, 440 Gotland's Lotion, 444 Milk of Roses, 445 Eau de Luce, 447 Red Saunders, 449 Civet, 449 Musk, 450 Ebony, 451 Ivory, 454 Tortoise-shell, 455 Roses, 457 Chemical Reagents, 460 TO JOSEPH LOVELL, M. B. SURGEON-GENERAL UNITED STATES ARMY, &C This volume is respectfully inscribed as a testimo- nial of respect and esteem, for his public and pri- vate character, manifested as well in the discharge of his official duties, with zeal and ability for the good of the service, as in those liberal and enlightened virtues, which not only distinguish the gentleman and man of science, but also the friend of rational free- dom, and the true philanthropist. By his friend and obedient servant, JAMES CUTBUSH, ADULTERATION OF FOOD, &c. In considering a subject so important and exten sive as adulterations, in its various details, and how sundry substances may be, as they frequently are. sophisticated, many of which being used for aliment, we necessarily inquire into the means of detecting them, and the use, as well as the action of re-agents in such cases. With respect to the adulteration of metallic and earthy preparations, sundry pigments employed by the painter, and substances made use of by the bleach- er, dyer, soap-maker, &,c. with a long catalogue of articles used in the arts in general; we may remark, that, as they are highly important, a knowledge of their purity must be particularly desirable, andtheii examination require a minute investigation. We purpose to consider, in the first place, the subject of water, connected with its purity and foreign admix- ture ; and proceed, in order, with the adulterations of wine, and of other substances. WATER. Water was formerly supposed to be a simple bo- dy, and was considered one of the four elements. It is nww known to be a compound of hydrogen and 1* ( 6 ) oxygen. Two volumes of hydrogen gas, detonated with one of oxygen gas, produces water. Water may be decomposed by galvanism, and its elements sep- arated in a distinct state; by passing its vapour through an ignited gun-barrel, by which the oxygen will be absorbed by the iron, and its hydrogen evol- ved j by mixing it with sulphuric acid, and pouring the mixture on iron or zinc, hydrogen gas being evol- ved j and by several other processes unncessary at this time to enumerate. Water freezes at 32 deg. and boils at 212 deg. Faht. It is the standard ofthe specific gravity of bodies : its specific gravity being called 1000. It dissolves various substances, and constitutes the water of crystallization of crystal- lized salts. It unites with the earths and some me- tallic oxydes, and forms hydrates. It is susceptible of compression, as was first shown by Canton, and more lately by our countryman, Mr. Perkins, who has estimated, in an ingenious series of experiments. the rate of its compression. Mr. Thenard has shown that water may be combined with a considerable ex- cess of oxygen, which has been named the per oxyde of hydrogen. The specific gravity of hydrogen com- pared with oxygen, is as 1 to 16 : and the compo- nent parts of water, by weight, are 1 hydrogen, and 8 of oxygen, nine being the representative number of water; or 100 parts of water consist of 88.89 oxygen. 11.11 hydrogen. 100.00 ( < ) The division of water into hard and soft is well known. Soft waters are certainly more wholesome than hard, as the latter contains sundry salts, princi- pally of an earthy nature. Soft water, for very ob- vious reasons, is preferable to hard for the purpose of brewing; in dyeing, as it does not alter the dye- >tufF, or the mordant; in bleaching, as it acts more powerfully on the colouring matter of the vegetable (ibre ; in the preparation of painter's pigments, as it is known that carmine, madder lake, ultramarine and Indian yellow, cannot be prepared without perfectly pure water ; in the steeping of flax, as hard water will not decompose the ligneous matter so effectu- ally ; in the culinary art, as in proportion to its pu- 'ity, it will soften the fibres of animal and vegetable matter more readily than hard ; for with the latterpeew, or any fasinaceous seed, cannot readily be boiled. without the addition of a little potash, which is re- commended in every cook book. The effect of hard and soft water may be shown on tea. With soft wa- fer, the infusion will have the strongest taste, although possessing less colour than the infusion made with oard water. With sulphate of iron it will strike a more intense black, and will give a more abundant precipitate with gelatin, which shows that it contains more gallic acid and tannin, both of which are contained in tea. But by far the best criterion of the purity of water, as respects its freedom from acids, and earthy and metallic salts, is its effect on soap : with soap it ought to form a clear solution; for, if it become in die least turpid, we may infer the presence of ( 8 ) either one or the other of these substances, as thai change is known to arise from the decomposition of the soap, either producing a disengagement ofthe oily matter, if an acid be present, or the formation. of insoluble soaps of the earths or metals, if earthy or metallic salts, at the same time the alkali uniting with the acid ofthe salts. As a more delicate test, the solution of soap in alcohol is employed, with the effect of which you are well acquainted. Common air and carbonic acid gas, are both contained in wa- ter; to these substances the taste or liveliness of spring water is owing, and hence the difference in spring and river water. The latter also contains air, but in a smaller quantity ; otherwise fish could not live in it. River water contains about 2.25 of car- bonic acid, and 1.25 of common air, in 100 cubic inches. Water is rendered pure, or free from for- eign matter, by distillation. Hard waters may be corrected by the addition of potash, which in general decomposes the earthy salts, leaving an alkaline salt in solution that does not act on soap. Rain water, next to distilled water, is the purest, which may be 'J readily proved by experiment. Snow water appears to be free from air. It is to snow water that some physicians ascribe certain swellings of the neck, which deform the inhabitants of many of the Alpine vallies. Common springs, which furnish us with water af- ter having traversed various strata, contain saline sub- stances in consequence of that filtration, as the wa- ter dissolves all soluble substances it meets with ; and ( » ) not unfre^uently such springs contain a variety of mineral substances, so highly impregnated as to re- ceive the name of mineral waters.* The most com- mon saline matter in spring water is muriate of so- da; but the hardness of water depends chiefly, eith- er on the presence of the supercarbonate or sulphate of lime, or sometimes of both. One grain of sulphate of lime in 2000 grains of water, forms the hardest spring water with which we are acquainted. * Mineral Waters have been defined, those waters which, by their peculiar smell, taste, colour, fcc. and cannot be applied to domestic purposes, differ from common spring water. Accord* ing to the peculiar substance which predominates in each, they have been divided into four classes, namely, 1. Acidulous, 3. Hepatic, 2. Chalybeate, 4. Saline. The acidulous waters contain a considerable proportion of carbonic acid, and have an acid taste. The chalybeate waters contain ironin solution usually dissolved by carbonic acid, which they deposite on boiling in the form of an ochre. The hepatic or sulphurous waters are distinguished by an hepatic smell, re- sembling the odour of rotten eggs, which is owing to the pres- ence of sulphuretted hydrsgen gas, and blacken silver. Saline waters contain only salts in solution, without iron or carbonic acid in excess. The contents of a mineral water are discovered by analysis. Tests or re-agents determine the presence of certain substances. We may remark here, that, with regard to well water, of which we shall speak hereafter, Solon established a law, predicated on the scarcity of spring and river water. He obliged wells to be dug; and "where there was a common well within a Hippicon, the people should use it; they that lived farther off should pro- cure water of their own, and if, when they have digged ten fa- thoms deep, they find not any, they might be allowed to fill a pitcher of six gallons, twice a day, at their neighbour's well.'V- Hi*t. PhUos. by Blame. ( io ) River water may be considered as merely a col- lection of spring and rain water. Bergman found the springs about Upsala, which are considered pure* to contain the following substances, viz. oxygen gas, carbonic acid gas, carbonate of lime, silica, common salt, sulphate of potash, carbonate of soda, and muriate of lime. The whole of these ingredients amounted at an average to 0.0004 parts. Having frequently examined spring and mineral waters in this country, we may remark, that we have always detected in the former, the presence of alkaline sul- phates and muriates, with frequently lime, and tra- ces of magnesia. With regard to the waters of West Point, the purity of which is proverbial, by-experi- ments made at different times; all these saline sub- stances we found to exist, although in a comparative- ly small proportion. Well water is essentially the Same with spring water, being derived from the same source. It is generally supposed to be less pure than spring water, on account of its stagnation or slow fil- tration. The well water of cities is excessively im- pure. A well in Philadelphia was supposed to fur- nish a mineral water, on account of its peculiar he- patic smell, as it possessed some of the characters of sulphuretted hepatic water, and was drank by many m consequence of its supposed medicinal properties, when it was finally discovered that the hepatic odour did not arise from the decomposition of sulphurets, or other natural cause, but was nothing more than a filtration of water through a neighboring receptacle! The fact, however, was admitted, that the well watet ( n ) inroughoutthe city was generally very impure; hence the present introduction of Schuylkill water, the nu- merous advantages of which are now appreciated. Mr. Sennebier has shown, that well water usually contains a greater proportion of carbonic acid gas, than spring or river water. Lake water is merely a collection of rain water, and is seldom so transparent as river water. It con- tains frequently decomposed animal and vegetable matter. Marsh water is altogether stagnant, and ie largely charged with animal and vegetable remains, to the decomposition of which the noxious miasmata of marshes is attributed. The deleterious effect of marsh air is particularly observable to the south. Rice grounds, which are low wet land, produce an abundance of this miasmata, and extend its fatal in- fluence for many miles. Since the rice culture near Savannah has been abolished, that city enjoys a greater degree of health. River water is the purest when it runs over a gra- velly or rocky bed, and when its course is swift. It is generally soft, and more free from earthy salts than spring water. In the new river water, near London, we are informed that a minute portion of muriate of lime, carbonate of lime, and muriate of soda, are con- tained. Although river water may,in general, be free from saline matter, yet it is often fouled with mud, containing much animal and vegetable matter, which are suspended in it. The water running by cities must be exceedingly impure. The river water of ( 12 > the Seine* near Paris, is foul in consequence of ma- ny circumstances. It is drank, however, after pas- sing through the filtering machines, which can only separate the substances that are mechanically, but not chemically combined with it. Mr. Du Com- mun's filtering apparatus is chiefly used for that pur- pose^ The water of the river Thames, m.the envi- *The quantity of gas obtained from the Seine water, was at anaverage0.0275ofitsbulk,ornotquitel-36 part; the average quantity of oxygen which this gas contained was 0.310.—Thom- son's Chemistry, iv. 612, English edition, 1820. •f Several contrivances for the filtering of water have been made; some of which have been patented. The filtration of river water is sometimes desirable, and, especially at sea, is often :ndispensable.' There does not require any arguments to prove the beneficial effects of pure soft water to the preservation of health. The filtering machine of Mr. J. Peacock, which has been generally in use, consists in causing the fluid to ascend through a medium of fine gravel, of progressive degrees of fine- ness. It does not require more room than a large drip stone, and yields more than 300 gallons in 24 hours. A filtering ap- paratus for the use of the navy was invented by Dr. E. Cut- bush, and found to answer its highest expectations. A view of the machine may be seen in Cutbush's Observations on the means of preserving the health of Soldiers and Sailors. Parrat, of Paris, also invented an apparatus for the same purpose, and so did Mr. Smelt ofthe same city, which purified water by pas- sing it through sponge, and then through alternate strata of chalk sand, and gravel. Moult's improved method of using the fil- tering stone, has likewise advantages. But of all that we are acquainted with, none is more portable and complete, and more effectual in its operation, than Mr. Du Commun's. It consists of an earthen jar furnished with a division in the middle, having an aperture of an inch or more in diameter, and a tube for the conveyance of air to the inner, or confined part of the jar. The middle, or confined part is filled with alternate layers of gravel, sand and charcoal, and all the water which passes through the ( 13 ) Hoiia or" London, is very impure. No water carried to sea becomes putrid sooner than that water. It ■ndergoes, however, a remarkable change in casks Iron tanks are used in the British navy in the place of wooden casks, which are said to preserve the wa- ter much better. The putrefaction which the Thames, and other water containing animal and vegetable matter undergoes, creates a very unwholesome smell, from the escape ofthe carburetted and sulphuretted hydrogen gases. During this change the water i* black and offensive. When racked off, and exposed to the air, it deposites a black slimy mud, and be- comes limpid.* A water, containing animal matter different strata, is first imperfectly filtered through a sponge, placed in the aperture above mentioned, made for that purpose. This is the apparatus so generally in use in the city of Paris, and occasionally in this country, for which Mr. D. has taken out a patent. When the filtering materials have become charged with foul matter, which happens in a greater or less time accord- ing as the water which is filtered is impure, they may be renew eel without difficulty: but, generally, for ordinary river water, one charge is sufficient for a twelve month, *The Rev. Mr. Clarke, in his Hundred Wonders oftht World, in speaking ofthe Thames water, says, that it "is justly esteemed exceedingly wholesome and fit for use in the longesi voyages during lohich it ferments, and becomes fine and clear!'" Why the Thames water should be ''exceedingly wholesome,'" when it is known to be exceedingly impure is rather contradic tory, especially wheri Mr. Clarke observes, that it is fit for use " in the longest voyages, during which it ferments," a fact that it is excessively impure? The superiority of English porter, as some give it the preference, is said to be owing to the water. with which it is made, viz. the water of the Thames! All soft water, i. e. water free from saline matter, is known to every brewer will make a better infusion of malt and bops than harfT ( 14 ) in solution, will give with nitrate of lead a while precipitate, which is soluble without effervescence in nitric acid. This precipitate is a combination of oxyde of lead, and animal matter. As to the mode of detecting saline matter in wa- ter, the usual course of analysis may be resorted to. The foreign salts are generally carbonates or sul- phates, and muriates of soda, lime, and magnesia. The distinguishing character of water, into hard and soft, may be determined by a solution of soap. The carbonic acid may be delected by lime or barytic wa- ter, the precipitate being soluble with effervescence in acids. Sulphuric acid is known by the addition of any ofthe soluble salts of barytes, with which it forms a precipitate, insoluble in nitric, or muriatic acid. Muriatic acid is known by nitrate of silver, -md the solubility ofthe precipitate in liquid ammonia. Iron is detected by tincture of galls, or the ferroprussiate of potash. Magnesia is known by adding first, car- bonate of ammonia, and then, phosphate of soda. The presence of oxygen may be discovered by the greeD or protosulphate of iron. We may proceed also, ac- cording to well known rules, to determine the pro- portion of these substances, if it be worth the trou- ble. water; but it is a question whether animal and vegetable mat- ter, and filth of every description, which exists in the Thames water, will improve beer or porter ! We have heard ol vessels taking in their water in the Thames, under a belief that it was better than other water, when it is represented to be so very im- 'pure, as to require to be fermented, filtered, &c. before it can be ( I5 ) With respect to the deleterious effects of keeping. water in leaden vessels, it seems that the ancients, 2000 years ago, were well acquainted with the inju- rious effect of lead, and of keeping water in leaden vessels. Although pure water, it is to be observed, does not act on lead, if air be excluded, and there- fore can have no effect upon it; the metal is certain- ly acted upon by the admission of air, a fact abundant- ly proved by some fatal accidents that have occurred in using water thus kept. The white line observed at the surface of the water kept in leaden vessels, is a carbonate of lead. The metal touches the water, and at the same time comes in contact with the air- The ancients condemned leaden pipes in consequence of this circumstance ; and persons, according to Sir G. Baker, who have swallowed the sediment of such a water, became affected with bowel complaints. Numerous instances, however, are recorded of fatal consequences ; whole families have been poisoned by water which had remained in reservoirs of lead, ac- cording to Van Swieten, and others. Hard waters, it is said, will corrode lead more rapidly than soft waters. The following facts stated by Sir G. Baker, are conclusive as to the deleterious effect of lead :— " A gentleman was the father of a numerous offspring, having had twenty-one children, of whom eight died young, and thirteen survived their parents. During their infancy, and indeed until they had quitted the j)lace of their usual residence, they were all rtmarka' bly unhealthy: being particularly subject to disorders of the stomach and bowels. The father, during ma- ay years was paralytic; the mother, for a long timt, was subject to cholics and bilious obstructions. Af- ter the death of the parents, the family sold the house which they had so long inhabited. The purchaser found it necessary to repair the pump. This was made of Jead ; which upon examination was so cor- roded, that several perforations were observed in the cylinder, in which the bucket plays; and the cistern in the upper part was reduced to the thinness of com- mon brown paper, and was full of holes like a seive." Besides the agency of air and carbonic acid, it is said that vegetable matter, as leaves, falling into a leaden cistern filled with water, imparts to the water a considerable solvent power of action on the lead. The saturnine cholic of Amsterdam, mentioned by Tronchin, originated from such a circumstance, and Other instances are mentioned of a similar nature. To discover the presence of lead in water, the usu- al tests are : water containing sulphuretted hydrogen gas, the hydrosulphuret and.hydroguretted sulphuret of the alkalies, and the celebrated wine test of Hah- neman, all which produce with the smallest quanti- ty of that metal, a dark brown or black precipitate. One part of acetate of lead may be detected in 2000 grains of water, so delicate is this re-agent. Other tests are recommended for the same pur- pose : sulphate of potash, or sulphate of soda, will detect minute portions of lead, as one part of lead in 100.000 parts of water. Dr. Thomson in recom- mending this test, remarks, that no other precipitate, (sulphate of lead,) can well be confounded with it,. ( 17 ) except sulphate of barytes, and there is no probabil- ity of barytes existing in common water. Carbonate of potash, or carbonate of soda, are al- so highly recommended to discover lead; but the precipitate produced, must not be confounded with the carbonate of lime, or of magnesia, as the salts of these earths may exist in a water, and be decompos- ed by the alkaline carbonates. With respect to the preservation of water at sea, several methods have been recommended, but none appear to answer so well as using fresh burnt char- coal, and having the staves of the casks previously charred. Dr. Butler has found, that four ounces of pearl- ash dissolved in 100 gallons of water, and the cask cleaned in the usual manner, will keep it sweet for eighteen months. Sulphuric acid, in a small por- tion, has a powerful effect on the preservation of wa- ter. Calcined allum and powdered charcoal, mixed together, have been used to restore putrid water; ten grains ofthe former to a gallon, is the proportion re- commended. Mr.Lowitzused 1 1-2 ounces of char- coal in powder, and 24 drops of sulphuric acid, to cor- rect the putrescency of three pints and a half of wa- ter. A few grains of lunar caustic to a hogshead .of water, .will prevent its putrefaction ; but putrid wa- ter may be restored to its original purity by filtering it through sand and eharcoal. In Boerhaave's Che- mistry is the process formerly used in the Dutch na- vy, for the preservation of water. In Lind, on Hot Climates, may be found a very economical method ( 18 ) of obtaining fresh water from sea water; it consist* in an economical arrangement of a simple distillatory apparatus. An economical method of obtaining fresh water from salt water at sea, when a scarcity ofthe former is experienced, must be highly advan- tageous to the mariner. In the navy, where the boilers are necessarily large, the supply of water might in this way be considerable ; each boiler be* rag furnished with a head, and condensing the aque- ous vapour in the usual manner. If we are not mis- taken, a plan of this kind is adopted in the British navy. The cooking by steam is altogether a saving of fresh water, as sea water can be used with the same advantage, and the salt left in the boilers saved for use. We perceive then, that saline matter when dissolved in water can only be separated, or the wa- ter rendered fit for drinking, by distillation ; where- as water which is merely fouled, or rendered turbid by earthy matter, as river water, is purified and made transparent by filtration. The common drip stone, or filtering stone used at sea, separates only those substances that occasion the turbidness of the water; but the filtering apparatus of Du Commun has a dou- ble advantage, in separating all foul matter, resulting from the putrefaction of animal or vegetable substan- ces, and at the same time all earthy substances m suspension. ADULTERATION OF WINE. Wine is frequently adulterated. To discover the adulteration in every particular, is a difficult and un- certain, undertaking.^ ( 19 ) Allum is used to give young and meagre wine & more lively colour ; Brazil wood, the husks ol elder berries, and bilberries, to impart to Port wine a rich purple tint; gypsum, to render cloudy white wine transparent; oak wood saw dust, and the husks of filberts, to give additional astringency to red wine; bitter almonds to communicate a nutty flavour; tincture of raisin seed to give flavour to factitioue port wine; and sweet briar, oris root, clary, elder flowers, and cherry laurel water, to form the bouquet of high-flavoured wines. The art of manufacturing spurious wine is a regu- lar trade in London, and, in fact, is largely practised in our own country. Cider is the article used for this purpose; it is generally poured on the lees of old wine, to give it the flavour and the tartar taste, then mixed with a due quautity of brandy or spirit. The Tatler, (vol. viii. p. 110,) alludes to these wine brewers, who work under ground in holes, caverns, and dark retirements, to conceal their mysteries from the eyes and observations of mankind. " These subterraneous philosophers," says the Tatler, " are daily employed in the transmutation of liquors, and by the power of magical drugs and incantations rais- ing under the streets of London, the choicest pro- ducts of the hills and vallies of France. They can squeeze Bordeaux out of the sloe, and draw Cham- paigne from an apple. Virgil in that remarkable • prophecy Incultisque ruckens pendebit sentibus uva. Virg. Eel. iv. 29 ( -20 ) The ripening grape shall hang on every thorn:— seems to have hinted at he art, which can turn a planta- tion of northern hedges into a.vineyard." Various Re- cipes are given for the manufacture of spurious wine. It will be sufficient for our purpose to remark, that in the so called fabricated British port wine, the juice of red beet root, logwood and rhatany are added to cider, with a due quantity of brandy ; and in the British Champaigne, white and brown sugar, and lemon acid are used with water, white grape wine and brandy, and suffered to ferment. Pink Champaigne is made of it by using preserved straw- berries and cochineal. What is called crusting in the wine trade, consists .in lining the interior surface of empty wine-bottles, in part, with a red crust of supertartrate of potash, by suffering a solution of that salt coloured red with a decoction of Brazil wood to crystallize within them. Staining the lower extremities ol bottle corks, with a fine red colour, to appear, on being drawn, as if they had been long in contact with the wine, is also a common practice. * In London, it is the business of the wine cooper to prepare the astringent extract, and " genuine old port," by the admixture of foreign and domestic wine; and the refiner of wine is employed in the mellowing and restoring of spoiled white wines. Sometimes the internal part of a cask is lined with an artificial red tartar. In this country we have known not only cider converted into Madeira, but also red or astringent ( 21 ) .fanes manufactured from it. Artificial red wines ai t usually made of cider, with the addition of spirit. the juice of the sloe, gum kino, or other red astrin- gent colouring matter; and white wines by adding to cider a due quantity of brandy, and digesting the mixture on the lees of wine, and imparting a flavour as occasion requires. A very delicious flavour may bo given by pine apple. The fact is well known, that wine merchants, ge- nerally, have been in the habit of purchasing cider. A wine merchant of one of our large cities, who amas- sed a fortune by the trade, purchased annually some thirty or forty hogsheads, which although not manu- factured under the street, as in London, was never- theless converted into Port, Madeira and Cham- paigne ; so well did he understand the magical art of squeezing Bordeaux out of the sloe, and drawing Champaigne from an apple! Fraudulent adulterations are practised with impu- nity, and paradoxical as it seems, the practice is jus- tified by not only wine merchants and dealers in li- quors, but by many others. The wine merchant will tell you thatr jfour wine wants a body, is prick- ed, &tc. and prescribes, secundem artem, the addition of brandy, wood ashes, and the like ; and that Ma- deira, in all respects equal to imported, he can imi- tate without sending all the way to the Madeira Is- lands; but when you purchase of him, he will sell you his pure, genuine, unsophisticated wine at the rate of from three to six or eight dollars per gallon, 3nd thus tax your purse for your credulity, and aotn* ( 22 ) ally give you his imitative wine! The manufacturer of mustard will justify his foreign admixtures, on the ground that the seed will not £rind without them ; and the chocolate maker, that his coco lost its oil, and will not pass through the mill without fat or lard! Good cider wine is wholesome. There is nothing particularly injurious in imitative wine made from cider, brandy, and wine lees, with or without the ad- dition of red astringent matter, as the sloe, kino, &c. But what we deprecate is the fraud, the deception actually practised by selling such wine as the impor- ted, and at the same price, with the duties and all included !* During the war, impositions of this kind were practised on the Hospital department of the army, some of which we detected. There is a preparation of cider, made by ferment* * Cider vnnt is prepared by boiling the juice of apples till one half is eyaporated, and the remainder is put into a wood- en cooler, whence it is barrelled, with the addition of a due pro- portion of yeast, and fermented in the usual manner. In three or fouryearsit is said to acquire the colour and flavour of Rhe- nish wine. In the west of England, seve/al hundred hogsheads of cider wine are annually prepared, and the hoiling is conduct- ed in copper vessels. Dr. Fothergill was the first who suppo- sed that this wine contained copper. He accordingly made a number of experiments, w>hich proved that cider wine prepared in that manner, does contain a minute portion of copper. We do not consider wine prepared by this process as meriting any preference, because tiie greater part of the juice must be volatili- zed, and consequently a considerable part of the essential in- gredient itself lost. Ciderkin is no other than a preparation *rom the lefts ofcider, and cider spirit, the cider distilled. ( M ) nig honey, which is bottled, and called " American Champaigne." Wnen the cork is drawn the quanti- ty of carbonic acid gas that is liberated is so great, as not only to produce a copious sparkling, but also a foaming. Cider bottled in this way, partakes more of the nature of hydromel, or mead, a beverage pre- pared by fermenting honey and water, which con- tains from two to three times its bulk of carbonic ;\cid. The " American Champaigne,*' as it has been na- med, is, therefore, a preparation of cider, the fer- mentation of which has been renewed by the addi- tion of honey added in a certain proportion. Al- though cider may be treated in this manner, clarified with isinglass, racked and bottled, and sold as bot- tled cider ; the briskness of which is owing not to the original carbonic acid produced by the fermentation of the juice of apples, but to that which is subse- quently generated by a new fermentation, and a lar- ger quantity of alcohol is also produced. We con- sider the addition of honey, under these circumstan- ces, by no means objectionable. Harsh cider is ve- iv greatly improved by it. Those who follow the business of preparing bottled cider for the market, frequently avail themselves ofthe use of honey. Ci- der which is pricked, or has become slightly aces- cent, is cured with a little pearlash; the effect of which is obvious by its neutralizing the acetic acid, thus generated. The acetate of potash formed, is perfectly harmless. A very grateful flavour to cider is imparted by orris root. ( 24 ) To prevent the escape of carbonic acid in the fer*- mentation of the juice of apples, or to retain a suffi- ciency to give the cider a 6mA; taste, cider makers have adopted several expedients. In the state of Connecticut, where much cider is made, it is a com- mon practice to pour a tumbler full of olive oil into the bung hole of every cask, which is said to retain the fixed air, but the fact appears doubtful. We think, however, that as the olive oil prevents the im- mediate contact of air, it must prevent the acescen- ey of the cider. Dr. Darwin assures us, that on an estate in England, where a considerable quantity of cider was made, the apple juice as soon as it had settled, was put in strong casks, and bunged up close, and that very few casks burst. This cider, we ma/ reasonably suppose, must have been supersaturated with carbonic acid* A handful of powdered clay is said to prevent a succeeding fermentation. To preserve it, apple whiskey is sometimes added. The "American wine," prepared by Mr. Cooper, of Gloucester county, N. J. according to his mode of preparation, is made by mixing with cider from the press a quantity of the honey comb, and after standing some time honey is added* until the strength of the liquor will bear an egg. After fermentation it is fined with the white ofeggs, and a sufficient quan- tity of common cider spirit added. Wine made in this manner, Mr. Cooper observes, would not cost a quarter of a dollar per gallon ! In the manufacture of artificial wine, the whole art consists in giving the liquor a sufficiency of bran- ( ■** ) dy, and of tartar, and imparting to it the flavour of the wine, as, for instance, Madeira; taking care at the same time, that it be neither too weak, nor too strong, and that the quantity oftartar.be rightly ap- portioned. In the preparation of artificial liquors, I mean for domestic consumption, as a mean of econ- omy, various expedients may be used, which will readily occur to those who are acquainted with the nature and properties of liquors. The expressed juice of grapes, which is a liquid of a sweet taste, called must, is composed ol water, .cu- e;;u, mucilage, gluten, and tartaric acid partly satura- ted with potash, and is decomposed by the vinous fermentation, in which alcohol is generated. If we inquire into the causes of the fermentation, the sub- stances present, the changes which they undergo, and the character and properties ofthe product, we will then have a knowledge of wine-making. In ordinary ca- ses of fermentation, alcohol is produced in combina- tion with water, mucilage, and probably undecompo- sed sugar, as in brewing some kinds of bper, as ale, and nothing remarkable is to be observed. But as the fermentation of must takes place without adding any ferment, Fabroni attributes it to the presence of gluten, which exists on the membranes of the grapes that separate the cells; whereas the saccha- rine part resides in the cells of the grapes. The- nard has shown, that all other juices that undergo a spontaneous fermentation contains a similar sub- stance ; and hence the formation of wine is the ac- 3 ( 20 ) lion of this glutinous matter on the saccharine sub- stance of the juice. The properties, such as the taste, ezc. of wine dif- fer very much ; and by the substances pre-existing in the juice, or taken up in fermentation, we deter- mine the character of the wine, inasmuch as it h either red or white, strong or weak, sweet or tart. Saccharine matter dissolved in water, and mixed with common vegetable gluten, with the addition of tartar, will ferment and produce a fluid analagous to wine; to which colouring matter, and if necessary, astringent matter may be added, and thus give an im- itation of red wine. It is then evident, that the al- cohol in fermented liquors is variously combined with water, colouring matter, sugar, mucilage, and the vegetable acids; and the art of imitating wines, he. depends altogether on imparting to the spiritouf fluid, the taste, flavour, colour, &c. of the original. Mr. Brande has shown, that the colouring and acid matter in wines may be, for the most part, separated in a solid form by the action of a solution of acetate of lead, and that alcohol may be then obtained by abstracting the water by means of hydrate of potash, or muriate of lime, without artificial heat. It is true that some colouring matter, and particularly tartaric acid, will combine with oxyde of lead, and form an insoluble precipitate, which may be readily recogui- zed; but when sugar of lead is used to correct the acescency of wine, which was formerly the practice, it is prejudicial in the highest degree, and ought to be discarded. ( 27 ) With respect to the use ofthe sloe, (prunus spino- sa,) in imitating red wines, a practice hinted at in the Tatler, it is remarked that its juice communicatee to them not only a red colour, but an astringent taste. If the juice of the unripe sloe be inspissated, it will have a strong resemblance to the Egyptian acacia. which is furnished by the mimosa nilotica. Some ot the lichens have also been used to impart colour to wine. Thus the calcareous lichen, (lichen calcare- ous,) which is found in limestone rocks, will give a rich colour; and the orchall, or dyer's lichen, (lich- en rocella,) furnishes a rich purple colour. But the substances which may be used as colouring matter. are almost innumerable. The original colouring matter of red wines, it is known, resides in the husks ofthe grape; and when the must is fermented on them, the moment the alcohol is generated, it acts upon and dissolves it. A contrary procedure produ- ces white wine. A short account of wines may be useful at this time. Several species of the vine are cultivated. but by far the most important of the whole is the common vine, the vitis vinifera, of Linneus. It is hardly necessary to add, that the grapes are put in presses similar to our cider presses, or according to the ancient method, by treading them with the feet in order to obtain the juice. The characteristics of the ancient vintage is expressed very strongly in the predictions of Isaiah concerning Moab : '; And glad- ness is taken away, and joy out ofthe plentiful field; und in the vineyards there shall be no singing, neith- ( 28 ) er shall there be any shouting; the treaders shall tread no wine in their presses; I have made their vintage shouting to cease." Wine, it is known, con- tains more or less carbonic acid gas, if bottled be- fore the fermentation ceases; and hence it frequent- ly breaks the bottles which contain it. The ancients usually kept their wine in skins, or leathern bags, well secured at the seams. The following passage in Scripture, refers to the effect of carbonic acid in new wine : "Neither do men put new wine into old bottles, else the bottles break, and the wine runneth out, and the bottles burst; but they put new wine in- to new bottles, and both are preserved." The difference of wine does not depend so much on the species ofthe grape, as in the quality of fruit, produced by the varieties of soil, cultivation, and climate. The peculiar mode of fermentation, and the state of the grapes at the time, must also influ- ence the quality of the product. Of Portuguese wines, none are so much in repute as the red port, which takes its name from the city of Oporto, in the neighbourhood of which it is made* There is also the white port and Lisbon. Of French wines, that usually considered the best is Burgundy, a red wdne of very delicate flavour. Claret is the only French red wine in demand. Champaigne possesses the most celebrity of the white wines. This is of two kinds, the sparkling and the still; the former is produced by bottling it before the fermentation ceases, by which an insensi- He fermentation, more properly speaking, takes ( 29 ) place; and the latter, or still Champaigne, by suf- fering the wine to go through the whole process of fermentation. Frontignac and Muscadel are also white wines, the production of Languedoc. Of Spanish wines, is the Sherry, prepared from the grape of Andalusia; the Rota, in Seville; the Malaga, prepared in the neighbourhood of Malaga; some inferior red wines; the Alicant; and a sweet red wine called Tent. Of Italian wines, which are now generally thin and bad, notwithstanding the ancient celebrity of ma- ny of the wines of Italy, we may mention the red wine called Lachryma Christi, prepared in certain vineyards on Mount Vesuvius. Of German wines, the most celebrated are Tokay, Hock, Rhenish, and Moselle, some of which are highly prized. Of the Madeira and Teneriffe wines, we may con- sider them generally as superior. The Madeira is considered by far the most valuable, particularly af- ter it has been ripened by conveyance into a hot climate. The number of pipes of wine annually made in the island of Madeira, is about 30,000. The grapes are put into wooden vessels, and the juice is extracted by persons treading upon them. The Canary Islands furnish rich white wine un- der the name of Canary sack, but more commonly called Malmsey Madeira. The genuine Malmsey, however, is the produce of Malvesia, one of the Greek islands. Teneriffe wine, when a few years old, has much the flavour of Madeira; but it then 3* ( 30 i becomes sweet and mellow, and resembles Malaga. Of Cape wines, produced at the Cape of Good Hope, there are two kinds, peculiaily rich, sweet, and deli- cate, called red and white Constantia, which are made at a vineyard situated about eight miles from Cape Town. The grapes of this farm, owing to some pe- culiarity in the soil, are superior to any other in the whole country. The annual produce, however, is small, seldom exceeding sixty pipes of the red, and 100 pipes of the white wine. In the United States several attempts have been made to cultivate the grape, for the manufacture of wine; some of which proved successful. Wine, on a small scale, has frequently been made in families, who have raised the grape for their own use. I al- lude, however, in particular to a settlement near Pittsburg, called Harmony; and to another by the same emigrants at Vevay, in Indiana. The quanti- ty now made, I am informed, exceeds all former cal- culations ; but it has not been manufactured in suffi- cient abundance to become a general article of trade. That various sections of the United States are well adapted to the cultivation of the grape, I presume is generally admitted. The cultivation of the grape should be encouraged as correct policy in our polit- ical economy, since the consumption of wine is so great, and large sums of money are annually expend- ed in the purchase of it. By producing within our- selves a sufficient supply of wine, if even we were lo manufacture no other than that recommended by the late Mr. Cooper of Gloucester, New-Jersey, by using honey and cider, the importation of wine would be rendered unnecessary. Thus we should keep a large amount of capital at home, which now passes into a foreign channel; for it ought to be remember- ed, that with wine, as with many other articles we import, the, so called, balance of trade is against us. It is true that the tariff exacts one dollar per gallon duty on Madeira wine, which affords a revenue to government of a considerable amount, but this is on- ly an indirect tax on the consumer, who in every instance, pays indirectly all costs, all duties, both foreign and domestic, on every article imported. If the produce of the farmer were taken in exchange, the trade would be equal. Many sophistications of wine are practised with impunity,and are considered legitimate with those who pride themselves for their skill in the art of manag- ing, or, according to the familiar phrase, of doctoring wines. When wine is adulterated with substances deleterious to health, they must of course prove fatal. This was the case with several persons who unfor- tunately drank of them ; a statement of which is giv- en in the British Monthly Magazine. Lead is the most deleterious substance which has been added to wines, and it was usually introduced in the form of sugar of lead. It was supposed to check the acesence of wine, as well as destroy any acid, and to render turbid wines clear. Wine merchants at one time believed, that the lead was perfectly harmless ; and some alleged, that none of the metal remained in the liquor; both of which are contrary to fact. In what* I 32 ) ever state lead is received into the stomach, it pro- duces disease; and although wine may contain but a small quantity, like the water in leaden cisterns, yet it acts as a slow and constant poison. Toffania, the celebrated female poisoner, who followed the infa- mous practice of preparing and vending poisons, could not, perhaps, have prepared a much more fa- tal slow poison than sugar of lead dissolved in wine. But the action ofthe lead on the system, it will be observed, is more or less great, according to its quan- tity and the quantity of wine daily used. The adulteration of wine with lead was at one time a common practice in Paris. In Graham's treatise on wine-making, lead is re- commended to prevent wine from becoming acid ; and to prevent, or cure its muddiness, a lump of sugar of lead, of the size of a walnut, and a table spoonful of sal enixon, are recommended for 40 gallons of wine ! The solution of litharge, or the semivitrified oxyde of lead, in vinegar, (subacetate of lead,) was used to soften grey wine. Without understanding its chemical combination, or that it was pernicious, the ancients were acquainted with the fact, that lead ren- dered, apparently, harsh wines milder. When its effects were discovered, they were ascribed to some other cause. When the Greek and Roman wine merchants wished to try whether their wine was spoiled, they immersed in it a plate of lead; if it be- came corroded, they concluded the wine was spoil- ed. Besides the fraudulent practice of adulterating ( 33 , wine with, lead, a practice which, happily for man- kind, is now abolished to the best of our knowledge, lead may occasionally gain admission into wine, ei- ther unsuspectingly or inadvertantly. Shot, for in- stance, which contains both lead and arsenic, is used in cleaning of wine bottles, and by rolling against the sides ofthe bottle, detaches the supertartrate of pot- ash, and is acted upon. This practice of cleaning bottles has led to serious consequences. A gentleman, whose friend was taken ill by drinking out of a bottle, on examining the dregs that remained, discovered a row of shot wedged forcibly into the angular bent up circumference of it, which, when examined, crumb- led into dust, the outer crust (defended by a coat of black lead, with which the shot is glazed,) being left alone, unacted on, whilst the remainder ofthe metal was dissolved. The proper counter poison for a dangerous dose of sugar of lead, is a solution .of Epsom, or Glauber salts, which forms an inert sulphate of lead. The Greeks and Romans were accustomed to boil their wine over a slow fire, till a half, third, or fourth part of it remained, and to mix it with bad wine in order to improve it. When by this operation it had lost part of its water, and had been mixed with honey and spices, it acquired several names, such as mustum, mulsum, sapa, carenum, &c. Most of those authors who have described this method of boiling wine, ex- pressly say, that leaden or tin vessels must be em- ployed. The method of improving wine by therse of lime, still practiced in the Island of Zante, in ^ue. ( 34 ) and on the coast of Africa, is not to be considered in- jurious, as nothing but either an acetate or tartrate of lime would result; but with respect tc the alcohol- ic part, it is impossible by this, or any similar pro- cess, to re-produce it. The tartrate of lime is insol- uble. Calcined shells were in ancient times used instead of lime. They are occasionally used by the moderns. Potter's earth was also made use of, to clarify wine. The oldest account of the poisonous sweet- ening of wine, is that which occurs in the French ordinance of 1696. In Germany, an order was is- sued in 1697, forbidding the use of lead, bismuth, sulphur, he. under pain of death, and confiscation of property, as well as being declared infamous. One person was detected in using litharge ; another, about eight years after, named John Jacob Ehrni, of Eslin- gin, was also detected and was beheaded. The fumigating of wine with sulphur, performed by kind- ling rags of linen, dipped in melted sulphur, and suf- fering the fumes or sulphureous acid gas to enter the cask partly filled with wine, was supposed to stop the fermentation of wine, and prevent it from spoil- ing. The acidity of wine may Errise either from a super- abundance of tartaric acid, or from the presence of acetic acid, the result of the acetous fermentaticn.— The latter indicates either the want of a sufficient quantity of alcohol, or the existence of more than is usual of mucilaginous matter. To correct the acid- ity of wine in either case, calcined oyster shells arc •A('35 ) ►ciieraiiy recommended. As burnt shells are n«- thino more than lime, a lump of quicklime will an- swer oqpally well. In the place of quicklime, com- mon chalk (carbonate of lime,) may be used with more certainty, as no more will be taken up than the acid will combine with. The lime, in both instan- ces, will form with tartaric acid an insoluble tartrate, which will fall to the bottom ; and with acetic acid, acetate of lime, a salt of considerable solubility.— Potash will have the same effect. Three methods have been used for the clarification of wine, viz.: the use of isinglass, of skimmed inilk, and the white of of eggs. The first unites with foreign substances in ^spension, or with tannin, if present, and gradually precipitates ; the second is decomposed by the acid of the wdne, and the curd is separated, which envel- opes the foreign matter, and falls with it to the bot- tom; and the third is coagulated by the alcohol in the wine, and the coagulum is precipitated in a sim- ilar manner. The re-agents for detecting the presence of lead in wine are several. The arsenical liver of sul- phur, was formerly a test to discover the presence of lead. The solution was called liquor probatorius Wurtemburgcius, having been applied for that pur- pose by a public order of the duchy of Wurtemburg. The wine test, as is called, which consists of water, impregnated with sulphuretted hydrogen gas, di- luted with muriatic acid, k the most ready re-agent to detect the presence of lead, or any other delete- rious metal in wine. The sulphuret, or hydro-sul- «r ( 36 ) phuret of lead, thus produced, is of a dark brow*, or black colour, which when dried and fused before the blow pipe on charcoal, yields a globule ofmetal- ic lead. In consequence of the presence of muriatic acid, this test has no effect on iron—a harmless me- tal. Any ofthe alkaline hydro-sulphurets, hydrogur- etted sulphurets, or hepatic gas, may be used for the' same purpose. Hahnemann wine test is made, by putting a mixture of 36 grains of sulphuret of lime, and 26 grains of supertartrate of potash in an ounce phial, and filling it with boiled water. The liquor after having been repeatedly shaken, and allowed to become clear, may then be placed into another phi- al, and 20 drops of muriatic acid added. It is suffi- cient to remark, that in consequence of the decom- position of the water, sulphuretted hydrogen gas is produced, which combines with the water, and at the same time we have ahydroguretted sulphuret of lime, with sulphate of lime. The addition of muriatic acid is to prevent the precipitation of iron. This re-agent produces, both with lead and copper, without enu- merating some other metals, a dark brown or black precipitate. Wine, previously acidulated with mu- riatic acid, if brought in contact with sulphuretted hydrogen gas, will instantly show if it contains lead, and this mode of using the gas is the most active. Subcarbonate of ammonia, besides carbonate of soda, is considered a very delicate test for lead, which it precipitates in the state of a white carbon- ate. This carbonate, when washed or digested in water, containing sulphuretted hydrogen gas, will inr ( 37 ) srtantly become black. If this precipitate be gently heated, it will become yellow, and, on charcoal be- fore the blow pipe, will yield a globule of lead.— Chroinate of potash will throw down from saturnine solutions, a beautiful orange yellow powder, the chremate of lead. It is said, however, that Burgun- dy wine, and all those that contain tartar, will not retain lead in solution in consequence ofthe insolu- bility ofthe tartrate of lead. The presence of acetic u id, winch is frequently the case, will always acton, and dissolve lead. Mr. Nicholson recommends the evaporation of wine, supposed to contain lead, and exposing the ex- tract with charcoal to the action of heat in a crucible. by which metallic lead will be obtained. With respect to the extraneous colours in red wine. Mr. Vogel, as well as Mr. Brande, has recommend- ed, as a lest, the acetate of lead. The substances usually employed for colouring wine, such as bilber- ries, elder berries, and Cam peachy wood, do not produce a greenish grey precipitate, as with genuine red wines. The precipitate, which these substances give, when infused in wine, is of deep blue colour. Brazil wood, red saunders, and red beet, produce a colour which is precipitated red by acetate of lead. Lime water will render wine, coloured by the beet toot, colourless ; but acids restore the colour. Red wine, prepared from black grapes, produces a greyish green precipitate with acetate of lead ; and the same effect takes place when the skins of grape, digested 4 ( 38 j in alcohol, are mixed in the form of a tincture, with acetate of lead. In concluding this subject, it may be proper to add, that all wines contain more or less alcohol, which depends on the quantity of saccharine matter contain- ed in the must, previously to the vinous fermenta- tion, and on which the strength of wine depends: that the sparkling Champaigne owes its particular character to the presence of carbonic acid gas, which is produced by insensitive fermentation after the wine is bottled ; that white wines are produced when the must is separated from the husk of the grape, and red wines when it is suffered to ferment on the husks, by which their colouring matter is taken up ; that wines by distillation furnish brandy, a liquor com- posed essentially of alcohol and water ; that they contain also a free acid, and hence they turn litmus, or tincture of cabbage red, which acid is naturally the tartaric, and also a small portion of supertartrate potash and extractive matter; and in general, that they differ from each other in flavour, taste, colour, and strength, some containing as low as 12 per cent. as Hermitage, and others on the contrary, as much as 26 per cent, of alcohol, as the Lissa, Raisin, and some of the Madeira wines. With respect to home-made wines, it may be ob- served, that as the gooseberry, currant, the cherry, &lc. furnish vinous liquors by fermentation, the quan- tity of spirit which they contain must be variable, without considering that which is added in preparing some ol them. The acid in home made wine is ( 39 ) principally the malic, while in grape wines it is the tartaric. In consequence of this circumstance, the use of supertartrate of potash is recommended. The juice ofthe gooseberry, as it is said to con- tain some portion of tartaric acid, is the best suited for making good wine. With respect to the sweet mucilaginous domestic wines, usually formed by the addition of a larger quantity of sugar, they are gen- erally too sweet to be pallatable to most persons; and besides, there is a deficiency of alcohol, on ac- count of which, they are apt to grow vapid. This deficiency, however, is usually remedied by the ad- dition of brandy, or more commonly ordinary whis- key. The addition of tartar, we are of opinion, would considerably improve such domestic wines. ADULTERATION OF BREAD. Bread is that substance which is prepared from certain grains, as wheat, or rye, previously ground by a mill into flour. The difference between leav- ened and unleavened bread, is, that the first is pre- pared with leaven, or a dry ferment, a practice which is ancient, and the latter without the use of fer- mentable substances. The unleavened bread is al- so very ancient, and is frequently spoken of in scrip- ture, (specially in the pentateuch. Biscuit may be considered as unleavened bread. The presence of gluteu is essential in making raised bread ; hence wheat, rye, he. as they contain it, along with starch and saccharine matter, makes the most perfect bread. Certain substances, as potatoes, rice, &tc. although ( 40 ) *hey contain an abundance of starch, will not make bread without the addition of gluten ; hence they re- quire wheat or rye flour. The theory of bread-mak- ing, or panification, is no other than, by the yeast which is added to cause the fermentation, the com- bined effect of the vinous and acetous fermenta- tion ; the carbonic acid being prevented from escaping by the gluten which suffers expansion. The baking puts a stop to the fermentation. Allum is often used in bread-making, which is said to impart a degree ofwhiteness,thatcommon flour will not receive in panification. This process is called the bleaching of ilour. ltis,however, injurious, and the best superfine flour, needs no addition of the sort. The smallest quantity used, to produce a white, light, and porous bread, is 4 ouncest o 240 pounds of flour. It is mixed with k either in the state of powder, or in solu- don. Another substance used by bakers, is subcarbon- ate of ammonia, with which they produce a light and porous bread, from spoiled,or what iscalled sour flour. This salt causes the dough to swell into air bubbles, which carry before them the stiff dough, and thus it renders the dough porous. None of the carbonate, however, remains, as it is volatilised by the heat.— Potatoes, in bread-making, are frequently mixed with flour; but they will not make good raised bread without gluten, as before noticed. Gypsum,* chalk. * History has recorded the treachery of one of the Bizan- une emperors, who, it is said, mixed powdered gypsum with the meal designed for the army of Conrad in, by which the greater part is said to have been destroyed. It is a fact, however, that ( 41 ) ma pipe clay, have also been used in the sophistica- tion of flour, or the making of bread. Carbonate of magnesia has been recommended by Mr. E. Davy, who observes, that when mixed with flour, in the pro- portion of from 20 to 40 grains to a pound of flour, materially improves it for the purpose of making bread, and that it is superior to carbonate of potash, especially with new flour. One pound of carbonate of magnesia is sufficient to mix with 256 pounds of new flour, or at the rate of 30 grains to the pound. When the flour is ofthe worst kind, forty grains to a pound are the proportion recommended. Mr. Davy conceives that not the slightest danger can be appre- hended from the use of 60 innocent a substance, es- pecially in such small proportions. Carbonate of mag- nesia is used in the preparation of some particular kinds of biscuit. The Boston crackers, for instance, are said to he made with it. Aerated soda water ad- ocd to flour, we have been credibly informed, makes a light bread. But to produce good bread, a regulai fermentation (the vinous and acetous,) is required.— The detection of allum in bread may be effected in an easy manner. If some ofthe suspected bread be digested in water, and the solution concentrated by boiling, and then muriate of barytes added, if al- lum or sulphuric acid be present, a copious white precipitate wjl' ensue, which will not disappear by .gypsum, in common life, is neither dangerous nor fatal. Wi.en found in \\ at or, the only effect it has, when the water is drank. ■« to produce a constipation. Lime-stone water*, howe-or onerate usually in a contrary manner 4# ( 42 ) the addition of pure nitric acid. Bread, made with- out allum, treated in the same manner, produces merely a slight precipitate, which is occasioned by a minute portion of sulphate of magnesia contained in the common salt used in the seasoning of the bread. Muriate of barytes, it is obvious, is calculat- ed merely to discover the presence of sulphuric acid ; but to detect all the constituent parts of allum, viz. the sulphuric acid, alumina, and potash, so as to de- termine its existence, we must proceed in a different manner. Having decomposed the vegetable matter ofthe bread, by the action of chlorate of potash, by exposing a mixture ofthe two to a red heat in a pla- tinum crucible, the residuary mass will consist of al- lum. It may be examined by muriate of barytes, for sulphuric acid; by ammonia, for alumina ; and by muriate of platinum, for potash. The earthy adulter- ations are easily detected by incinerating the bread at a red heat in a shallow vessel, and heating the residuary ashes with a little nitrate of ammonia.— The earths themselves will then remain, character- ised by their whiteness and insolubility. Lime may be detected by solution in nitric or muriatic acid, and the addition of oxalate of ammonia; magnesia, by adding to the solution, first, carbonate of ammo- nia, and then phosphate of soda, or by a copious pre- cipitation on the addition of potash. The goodness of flour depends on the due proportion of gluten, as well as of starch ; and as flour mates good fermenta- ble bread inconsequence of the gluten, its quantity is ( 43 ) determined, as well as the quality of the flour, by kneading it in water. The best kind of wheat flour assumes by the addition of water a very gluy ductile, and elastic paste. Flour, it will be seen, consists essentially of starch and gluten; and no fa- rinaceous substance will make raised bread, whate- ver may be the proportion of fecula, unless it contains a due quantity of gluten. ADULTERATION OF BEER. Malt liquors, of all kinds, have been more or less adulterated ; and fraudulent brewers and others have been convicted of preparing and using a variety of deleterious substam es, among which we may men- tion cocculus indicus, and nux vomica. Sun- dry colouring substances have also been employed. Thus, burnt sugar, or sugar colouring, has been ad- ded to porter: and to communicate a more bitter taste, quassia wood and wormwood have either been used with, or substituted for, hops. This practice h the same for all beer brewing. Nothing, how- ever, according to British statutes, is allowed to enter into the composition of beer, but malt and hops.* Quassia gives a very good bitter, but the * Malt is barley which has been partially germinated, then torrefied, and ground in a mill. By the operation of malting, the grain developes certain principles ; first, that which is ante- cedent to the growth of grain, and which is shown by pushing forth its radicle, the consequent effect of a change in the fecu- la, and gluten in particular; secondly,the change which these principles undei ga by drying and torrencation,as they undoubted- ( 44 ) -oops possess a more agreeable aromatic flovour, be- sides partaking iri an eminent degree ofthe bitter and ly give colour to the malt liquor, in proportion to the degree of kilndrying. This colour is owing more to the saccharine mat- ter than anything else; which undergoes an analogous change in the preparation ofthe liquor colouring. At the time of the ripening ofgrain, the saccharine matter it contains, as well as that carried by the sap vessels, coagulates and forms the fecula or starch; but in malting, the starch of the grain is converted into sugar,"in all probability by losing a little carbon, because there is a small absorption of oxygen, and consequent forma- tion of carbonic acid. What other immediate changes take place, in theproximate.principles,ar« of little moment. Starch, however, is convertible into sugar, ;by means of dilute sulphuric acid ; an A the acid is afterwards removed by using plentifully of lime water. It is therefore evident that the process of malting is no other than artificial germination; that the starch ofthe cotyledon is changed into sugar, which sugar, is afterwards, by fermentation, converted into spirit, and that the process should be carried on no farther than to produce the sprouting ofthe. radicle, which should be checked as soon as this has made its distinct appear- ance. If carried too far, so as to occasion the perfect develope- ment ofthe radicle and the plume, a considerable quantity of saccharine matter must necessarily be consumed in their ex- pansion, and hence barley, malted to that degree, will produce iess spirit by fermentation. Brewers have a method of discovering whether malt has been snade with mixed or unripe barley, by throwing a handful into a bowl of water; when the grains that have not been malted will •sink, the half malted grains will have one end sunk, and swim m a perpendicular position, and those that are perfectly malted, ^will swim. Beet roots have been substituted for malt, when deprived of their juice by pressure, and dried, and the beer is said to be little inferior to that prepared from malt. In some parts of Ireland, parsnips are also used ir> lieu of malt, in brewing. The young ( 45 ) .arcotic principle. B< < :, rendered Hirer by quas- sia, will not preserve as well as the ordinary hop beer. The fine frothy head, characteristic of good beer, called the cauliflower head, is said to be im- parted by a mixture of green vitriol, allum and salt; but this addition is generally made by the publicans. The sulphate of iron, alum, and common salt, may he readily discovered in the usual manner. It is said, however, that the sulphate of iron, added lo? hat purpose, does not possess the power ascribed to it. After fining.a butt of beer, the publicans fre- quently adulterate the porter with table beer, and a small quantity of molasses, and sometimes with £ small portion of the extract of gentian root, to pre- serve the bitter of the porter. Those who make it a business to bottle portei-from the cask, are very of- ten addicted to these practices. I have known a bottler who put up porter, that when he purchased his butts of porter from the brewer to sophisticate it: not that the porter required any addition, but for the purpose of improving it, secundem artem ; i. e. by nixing it with stale porter, molasses and water, r-> fermenting, and adding, occasionally, some bitter ex- tract, either of quassia or gentian. This species of brewing, like many other frauds we shall have occa- sion to notice in our remarks, is calculated, of course to increase the quantity of porter, and also the pro- fits. tops of the common heath, or ling, with half their quantity ot malt, forms a very goad beer to the inhabitants of Isl.o. o.*e oi the islands of ImoU.ukL ( 46 ) To recover sour beer, in which acetic acid is formed, it is not an uncommon practice to add cal- cined oyster shells; and for the same purpose, to restore pricked or stale beer, carbonate of potash is used, or in lieu thereof, some wood ashes put into a little bag, and thrown into the cask. In either case, the acetic acid will be absorbed, but the acetate of lime or of potash, will remain in solution. To impart a pun- gent taste to insipid beer,both capsicum or red pepper, and grains of paradise are employed. In some parts of Sweden, buck bean (menyanthes trifoliata,) are em- ployed in brewing, in the place of hops; two ounces of which being considered equal in strength to a pound of hops. Ginger root, coriander seed, and orange peel, are also employed to give a particular flavour. The in- toxicating quality of beer is increased by cocculus indicus, and an extract prepared from it, called hard multum; and, in addition, to produce a narcotic ef- fect, opium, tobacco, nux vomica, and extract of poppies.* * Cocculus indicus, or fruit ofthe menigpermum cocculus, has been long in use in brewing. The bitter principle ofthe coc- culus is called the picrotoxin, and when swallowed it intoxicates and acts as a poison. For the purpose of producing a temporary effect on fish, with the view of taking them, cocculus indicus has been used. A paste is made of cocculus, cummin seed, fenugreek seed, and coriander seed, equal parts, and made into balls ofthe sizeof peas, and thrown into ponds or creeks. The fish eat of it, rise to the surface ofthe water almost motionless, and become an easy prey to the fisherman. Before fish, caught in that manner, are eaten, it is necessary to put them in wat*M &I sometime, until they entirely recover. I 47 ) The detection of deleterious vegetable substances, 'o complicated in their nature as they are, although many ofthe proximate principles are characterised by certain distinguishing properties, is extremely dif- ficult; and, in fact, when combined with each other, beyond the reach of chemical analysis. liter which contains sulphate of iron, may be tested with muriate of barytes ; and the precipitate, if any, collected, dried and ignited, and, if insoluble in nitric acid, the presence of sulphuric acid is in- ferred. Tincture of galls, strikes a black in beer which contains iron. Genuine old beer may produce a precipitate with muriate of barytes, but the precipi- tate in that case is soluble in nitric or muriatic acid. If beer, containing sulphate of iron, is evaporated io dryness, and the vegetable matter burnt away in a crucible by the action of chlorate of potash, the res- idue will consist of sulphate of iron, which, when dis- solved in water, may be readily recognised by the usual tests for sulphuric acid and iron. The quantity of spirit contained in malt liquors, is readily known by distillation. The specific grav- ity of beer may point out the presence of some adulterations. The bitter principle of hops, quassia, Sic. in beer, is shown by a precipitation with acetate of lead. COUNTERFEIT TEA LEAVES. Tea has been counterfeited in several ways. Th- ( 48 ) leaves of the sloe, elder, ash, and of otiaei vegetable; have been used for the purpose, and persons have been convicted for employing them in London.— Other persons have also been convicted of using sun- dry leaves, and converting them into a spurious arti- cle, resembling black tea. The leaves v ere first boiled, then baked upon an iron plate, and, when dry, rubbed with the hand in order to form the curl, which the genuine tea had. The colour, which was afterwards given, was imparted by logwood. The manufacture of green tea they conducted by laying the leaves on copper plates, and adding Dutch pink and verdigrease. The presence of the latter is known by the well known blue colour it forms with ammo- nia. In forming black tea, sometimes a little ver- digrease was added in the boiling, along with the logwood. We may distinguish the genuiue tea leaf from the iloe, by comparing the botanical characters of the two leaves; but these characters can only be deter- mined when the leaves have been macerated, and unfolded. Spurious black tea, when moistened, gives a bluish black stain to paper, and in cold wa- ter affords a bluish black infusion, which changes to i ed by a drop or two of sulphuric acid. Genuine tea produces an amber coloured infusion,, which does not become reddened by sulphuric acid- The reason the acid produces a red colour with the sp riou- tea, is evident from the separation of the colouring matter ofthe logwood, used in giving the black colour to the tea. Mr. Accum assures us, that ( 40 ) all the samples of spurious tea, which he examined, were coloured with carbonate of copper, and not by means of verdigrease. Tea containing copper, if shook up in a phial with ammonia, will impart a Gnt blue tinge; and if thrown Into water containing sul- phuretted hydrogen gas, it will acquire a black col- our. Neither of these appearances take place with genuine tea. If tea coloured by copper be b'int with chlorate of potash, and the residue dissolved in nitric acid, the solution will be affected by ammonia as before noticed. It may be useful, perhaps, to notice, that th(> dried I eaves of an evergreen shrub, the thea bohea and thea vicides, of Linnaeus, furnishes both the black and green tea. Ol*black teas, is \he bohea or vooyc, so called from the country in which it is produced, and is collected sometimes at four gatherings. Alter the leaves have been partly dried, by exposure to the air or sun, they are thrown by small quantities at a time, into a flat cast iron pan, which is made very hot; they are stirred quick with the hand, then tak- en out, and rubbed between men's bands to roll them, and are again roasted over a slowjSre, which is usu- ally made of charcoal. The characters of the best bohea are, that it is a small blackish leaf, is dusty, and has a rough somewhat harsh taste. Congoo or cong-foo is also a black tea, derived from a word which implies much care and trouble. It is a superior kind of bohea, less dusty, with larg- er leaves. Souchong belongs to the same class.. It n><>f according to the respective proportions of al- cohol and water. The specific gravity of proof spri- it should be 0.916, temperature 60 deg., which corresponds with a mixture of equal parts of alcohol and water. There is, however, a difference of opin- ion on this subject. It may be proper to notice, that besides the use of the hydrometer, there are other methods of judging of the strength of spiritous liquors, which, however, cannot be depended upon for accuracy ; viz. the taste; the size and appearance of the bubbles produ- ced by shaking; the sinking or floating of olive oil when poured in it, and the appearance that it exhi- 6 ( 62 ) bits when inflamed. If it inflames gun powder when a portion of it is put in a cup and the liquor poured on, and set on fire; or if it burn away to dryness, or inflame cotton immersed in it, in either case it is considered as alcohol. The different spir- itous liquors, when burnt in a graduated vessel, leave variable proportions of water. Pure alcohol burns with a pale blue flame, scarcely visible in bright day light, and produces no fuliginous deposit, but merely aqueous vapour and carbonic acid, in con- sequence of the union of its constituents, hydrogen and carbon, with the oxygen of the air. One hun- dred parts of alcohol have been known, to produce in this manner, one hundred and thirty-six parts of Water. The flame of alcohol is coloured in a very remarkable manner, by the presence of certain sub- stances ; thus, from boracic acid, it acquires a green- ish yellow tint; nitre, and the soluble salts of bary- tes, produce a yellow flame; those of strontion, a beautiful rose red colour; and cupreous salts, a fine green tinge. With respect to the different modes of ascertaining the strength and quality of liquors, that by the taste is very uncertain. Sometimes a false strength is given by infusing in the liquor acrid vegetable substances, or by adding a tincture prepared with the grains of paradise and Guinea pepper. Brandy is often coloured with burnt sugar. The flavour of French brandy, in our opin- ion, is owing to a peculiar oil, and is often commu- nicated to rum or whiskey by distilling it over wine ( 63 ) lees, the spirit having been previously filtered through charcoal, or rectified over fresh burnt charcoal and quicklime. French brandies acquire by age a great degree of softness. Oak saw dust and a tinc- ture from raisins' stones, impart to new brandy and rum a ripe taste. Burnt sugar and molasses com- municate to factitious brandy, a luscious taste, and a degree of fulness. Imitative brandy is usually made in England, by adding to ten puncheons of brandy, 118 gallons offlavoured raisin spirit, 4 gallons ofthe tincture of the grains of paradise, 2 gallons of the cherry laurel water, and two gallons of the spirit of al- mond cakes, to whichare added 10 handfuls of oak saw dust, and a sufficient quantity of burnt sugar, to -give it, in the language of the trade, a complexion. The best brandy flavour, however, is the spirit of nitrous aether, or sweet spirit of nitre; even nitric acid added to liquor, will impart that flavour, in con- sequence of the gradual formation of the same.— Ground rice and charcoal, it is said, will make a brandy flavour. By diluting spirit or brandy, the acrimony of cap- sicum and grains of paradise, U it contain them, will then be readily discovered by the taste. Brandy that contains molasses spirit, or New England rum, is known by rubbing it between the palms of the hands ; or, if a portion be heated in a spoon over a candle, and inflamed, the residue after combustion, if from genuine brandy, will possess the vinous odour peculiar to that liquor, but if otherwise, will have a disagreeable smell, resembling gin or com- mon whiskey. ( 64 ) Arrack is imitated by adding to rum some pyrolig- neous and benzoic acid. The neutral liquor, as it is called, which is large- ly manufactured by the distillers in this state, is made of rye, but deprived of its usual taste and flavour; hence its name. This liquor is no other than whis- key-filtered through charcoal in a flannel filter. It is well adapted to receive the flavour, he. of either rum or brandy, but is more frequently used in adultera- ting them. For the purpose of improving the flavour of sun- dry liquors, and of communicating flavour to others, there is a method made use of, which wei have not mentioned. We are informed by a gentleman, on whose vera- city we can rely, that there is nothing which imparts a more grateful taste and flavour to liquor, either for improving that of rum, or communicating a more agreeable flavour to brandy, than the pine apple.— He has used it himself, and assures us, that, although a very expensive addition, the liquor is rendered ve- ry superior both in taste and flavour. Along with the pine apple, souchong has been added, which is said even to improve the taste and flavour. In order to preserve as well as improve the flavour of rum, twelve or fourteen pine apples are used for four hun- dred gallons of liquor. Liquors sometimes become milky or turbid when mixed with water. This effect is owing to the sep- aration of some volatile oil or resin, which was dis- solved in the spirit; for a mixture of spirit and wa- ( 65 ) ter will not dissolve an essential oil, as its solution depends on the alcohol. Very frequently brandy becomes nearly black, altogether by accident. Thi6 is attributed to nails or iron getting into the cask.— The cask, which is usually made of oak, is acted upon by the liquor, and the tannin and gallic acrid of the wood is taken up, which, by their union with the iron, produces the tanno-gallate of that metal.— There is no other way of getting rid of this colour, but by distillation; acids, indeed, would decompose the tanno-gallate, but then their presence would in- jure materially the liquor. If even an alkali were added to saturate the acid, it would be equally in- jurious, as it would cause the re-production of the tanno-gallate of iron, and consequently, the black co- lour. Gin is a liquor of a peculiar taste and flavour. It is a preparation of malt spirit, and is usually import- ed from Holland. Holland gin is considered the best, although domestic gin, especially that which bears the name of Pierpont, is now made nearly, if not of an equal quality to, and will bear comparison with, the imported. Age, and especially a sea voy- age, improves gin; hence, perhaps, why Holland gin has the preference. This liquor is characterised by the peculiar flavour of juniper berries, from which the raw spirit is distilled. Spirit of turpentine, how- ever, is too frequently added. Common gin ap- pears to be flavoured more with turpentine. Sugar »s sometimes mixed with this liquor, especially when diluted. Evaporating a portion of it in a spoon, will r?how it by leaving a residue of a saccharine taste- ( 66 > For the clarification of sundry mixtures forming fraudulent gin, alum and potash are usually added in succession, so that the alumina may be separated, and carry down with it the turbid matter. Alum is sometimes used alone. Shannon, on Brewing and Distilling, gives a pro- cess "to prepare and sweeten British gin," which consists in using oil of turpentine, oil of juniper ber- ries, alcohol, alum, he. Some of these substances are intended to impart the flavour, as the turpentine and juniper, and others again, to clarify the liquor when prepared, such as the alum. A method of fin- ing with sugar of lead has been practised, which un- doubtedly is highly reprehensible, notwithstanding a solution of alumis afterwards added ; by which, some would believe, the whole of the lead is separated ;n the state of a sulphate. This is too precarious an experiment, where health is concerned, as the separ- ation of the whole of the lead must depend on cir- cumstances. The presence of lead in distilled malt liquors, may he detected by the re-agents before mentioned, Sundry substances have been used to give what is called a bead to spiritous liquors : such substances are chiefly of an oleaginous, resinous, and soapy na- ture. Thus, common soap has been added in a smaller quantity ; but the i-aud may be immediately discovered by adding a few drops of sulphuric acid, or in preference a solution of allum. Either will produce a milkiness. If the cause of the size, he. of the bead should be attributed to an oil, or a resin, ( 67 ; the fact may be verified by the addition of wa- ter, which will produce a milkiness, the intensity of which will be according to its quantity. POISONOUS AND OTHER CHEESE. Several instances have occurred in which cheese has been found contaminated with red lead, which was inadvertently introduced in it by the impute an- natto, employed for colouring it. Annotta, in conse- quence of its frequent scarcity, is adulterated with sundry substances, and its color heightened either by red lead or vermillion ; and, therefore, when em- ployed in the process of cheese-making, as a colour- ing ingredient, must prove injurious. One instance is slated, that the vermillion used in the adulteration, was found itself to be impure, being composed of a mixture ofthe real vermillion with red lead. If cheese is suspected to contain lead, the fact may be ascertained by macerating a portion of it in water containing sulphuretted hydrogen gas in solution, vhich will g'rve to it a dark brown colour. When milk is turned by a mixture of rennet, which is prepared by digesting the inner coat of the stom- ach of young animals, especially that ofthe calf, the curd is separated into an apparently solid mass. This caseous part when pressed in the usual manner, con- stitutes cheese. In this operation, for a particular reason, some cheese-makers cut the curd from time to time, and with a brass knife, for iron is supposed by many to give a bad flavour. This is the usual ( 63 ) practice in some British danes, according to Mr. Nicholson. This practice of using brass, which is an alloy of copper and zinc, may in particular in- stances be objectionable. If the milk becomes aces- cent, which is often the case after the spontaneous separation of the cream, this acidity being in conse- quence of the formation of lactic acid from the whey, and which in fact produces the spontaneous coagu- lation, and separation of caseous matter ; there can be no question, if there is the slightest acidity in the curd, that some of the metal will be dissolved and contaminate the cheese. Cheese, if thus contaminated, may be tested with ammonia. In this country, however, brass knives are not in use in cheese-making. In the manufacture of cheese, a very agreeable flavour is often imparted to cheese, especially the kind called Stilton, by preparing the rennet in an in- fusion of sweet briar, rose leaves and flowers, cinna- mon, mace, cloves, and, in short, almost every kind of spice and aromatic that can be procured. In Che- shire cheese, if it is intended to be coloured, anatto, or an infusion of marigolds, or carrots, is mixed along with the rennet. In the Hafod cheese, marigold, cloves, and mace are added. The Parmesian cheese is prepared of milk gradually heated in a copper cauldron, and afterwards coagulated; and when pressed, the outer crust is pared off, the fresh sur- face is varnished with linseed oil, and the convex side coloured red. The green Swiss cheese, usual- ly called " sap-sago cheese," derives its flavour from ( 69 ) the met dot plant, (Trifolium melilolus officin.) In die preparation of Dutch cheese, the curd is separa- ted from the whey by muriatic acid, which may be detected in it. It has a sharp saline taste. In Westphalia cheese, in the operation of mellow- ing, which is a kind ofputrefactive fermentation, ca- raway seed, pepper, and cloves are also used; and finally, to suit the palate of epicures, the cheese is well smoked in a chimney, as it seems, an its impreg- nation with pyioligneous acid, is considered by them an improvement! With cheese in general, it is given as an opinion, that the rank and putrid taste, of which they frequent- ly partake, is owing to a putridity in the rennet. t Where sundry plants or flowers are introduced into cheese, by infusing them previously with the rennet and water, either with the intention of communica- ting a flavour or colour, there can be no doubt ofthe introduction of deleterious vegetable substances through mistake ; "and although such accidents may but seldom occur, yet it is necessary for cheese-ma- kers to guard against them. We have heard of a number of persons, who were affected with a pain in the stomach, by eating of coloured cheese, and the sickness was only removed by ejecting it. It is well known to cheese-makers, that the good- ness of cheese depends in a great measure on the manner of separating the whey from the curd. The practice followed in many parts of Scotland of heat- ing the milk too much, breaking the coagulum in pieces, and forcibly separating the whey, is highly ( ™ J reprehensible, as the cheese is scarcely good for any thing. This whey, however, is delicious, especially that which is the last squeezed out, a proof that nearly the whole of the creamy part ofthe miik has been separated with the whey. On the contrary, if the milk be not too much heated, (about 100 deg. is sufficient,) the coagulum allowed to remain unbro- ken, and the whey separated "by very slow and gen- tle pressure, the cheese is good, but the whey is nearly transparent and colourless. Bad cheese, or that which has not been properly made, when exposed to heat, dries, curls, and exhib- its all the phenomena of burning horn ; whereas good cheese, or that which has been made according to the above principles, melts at a moderate heat; a fact that it contains a quantity of the peculiar oil, which constitutes the distinguishing character oX cream. The oxygala of the ancients, which occurs in the writings of Pliny, was a kind of cheese, the prepara- tion of which was described by Columella. In or- der to make it, sweet milk was commonly rendered sour, and the scum was always separated from it. Pliny mentions another kind of ancient cheese, which went under the name of caseus oxygalactium, formed from the caseous part of buttermilk, by the addition of some acid., and mixed and prepared in several ways. LTXTUUTi II. PEPPER. This article is subject to counterfeit. A spurious pepper is made of oil cakes, (the residue of linseed after expression,) common clay, and a portion of cay- enne pepper. These are formed into a mass, gran- ulated by means of sieves, and then rolled in a cask. But these artificial pepper corns, the momont water is poured upon them, fall to pieces, whereas the gen- uine pepper remains whole. White pepper is prepared from the black pepper. The process consists merely in removing the rind, or outer bark. This is performed by steeping it in sea water or brine, till the rind softens, which is then detached by rubbing it with the hand. White pepper does not communicate any colour to water, but black pepper infused in water gives it a brown colour, which reddens vegetable blues, and has the odour and taste of pepper. Alcohol, when digested on it, acquires a light yellow green colour. By distillation it furnishes an essential oil, which is soluble in alco- ( 72 ) hoi, and when the solution is diluted, is extreme!) pleasant. A decoction of pepper treated with an infusion of nut-galls, gives a precipitate, which dis- solves at 120 deg. Hence pepper contains fecula, as well as essential oil, and extractive matter. PIMENTO. Allspice, or pimento, is the berry of the Jamaica pepper tree, (myrtus pimento.) They are gathered at a certain season, and dried, and put into bags for exportation. Some planters kiln-dry them. The pimento which grows in the Spanish dominions, is inferior to the Jamaica; the berry is larger, and pos- sesses a weaker aromatic flavour. Allspice is so called from its resemblance in smell and taste to cloves, juniper berries, cinnamon, and pepper. As there is so great an affinity between this and the true clove, it has been proposed as worthy of trial, if the fruit, when first ripe, or the flowers picked off the tree, and dried, might not answer the same purpose as the Asiatic. Allspice should yield on distillation, an aromatic oil, and when digested in alcohol afford a pungent tincture. If counterfeited by oil cake, he. as the black pep* per, the fraud may be discovered in the same man- ner. f 73 ) CAYENNE PEPPER. Many species of the capsicum are used for Cay *nne pepper. The pods, when dry, are pulverised. It is sometimes adulterated with the red oxyde of lead, which may be known by treating the powder with sulphuretted hepatic water, as already describ- ed. If one part of the suspected pepper, and three parts of nitrate of potash, are projected into a red-hot crucible, in small quantities at a time, the vegetable part will be entirely destroyed; and the residue, when dissolved in nitric or acetic acid, may be exa- mined for lead in the usual manner. Red saunder.^ are also used to increase its quantity. The capsicum frutescens, commonly called Bar- bary pepper, is used for making, what the author of the Dictionary of Merchandise calls, "pepper pots." We do not know of any particular advantage in prepar- ing the capsicum in the manner mentioned by him; but as it may be useful to some persons, we here intro- duce it. (Dictionary of Merchandise, p. 163.) "• Take the ripe seeds of this sort of capsicum, and dry them well in the sun, then put them into an earthen or stone pot, mixing flour between every stratum of pods, and put them into an oven after the baking of bread, that they may be thoroughly dried; after which they must be well cleansed from the flour, and reduced to a fine powder : to every ounce of this add a pound of wheat flour, and as much leaven as is sufficient for the quantity intended. Af- ter this has been properly mixed and wrought, it ( 74 ) should be made into small cakes, and baked, then cut into small parts, and baked again, that they may be as hard and as dry as biscuits, which being pow- dered and sifted, is to be kept for use. The spice h prodigiously hot and acrimonious, setting the mouth as it were on fire. POISONOUS PICKLES. A variety of vegetable substances are pickled, as gerkins, beans, samphire (both the crithmum marati- mum and salicornia,) the green pods of capsicum, he. besides the cucumber. In consequence of the different directions for the preparation of pickles, especially for communicating a lively green colour, they differ very considerably* in taste and appearance. The use of copper, or of copper kettles, is highly pernicious. Copper or brazen vessels are usually employed for the scalding of vinegar, as it is called, previously, to its being poured on the cucumber, or other vegetable intended to be pickled. Books on cooking recommend certain formulae, in which copper is used in some shape as the colouring ingredient; as, for instance, boiling the pickles or the vinegar with copper coin, or suffering them to re- main a given time in brazen vessels. There are cases recorded of serious accidents hav- ing occurred by eating of pickles greened with cop- per. A young lady, while dressing her hair, amused herself by eating a samphire pickle-prepared in that ( '5 ) manner; she suffered most excruciating pain, ling- ered a few days and expired! There are two recipes in particular, which we shall notice, for greening with copper. One is in the Jlodern Cookery, which is a solution of verdi- grease in vingar; the other is in the English House- keeper, by boiling the pickles with half pence. It is now, however, generally known and admitted, that copper is decidedly poisonous, and hence these recipes are not used. But the practice of boiling 01 scalding vinegar in brass kettles, and then pouring it on the cucumbers, previously soaked in a solution of com:non salt, is still pursued in many families. We will here remark, that in all these instances, the green colour is imparted by acetate of copper, which i<= formed. Wholesome pickles may be made by soaking the cucumbers first in salt and water, and putting them with cider vinegar and cabbage leaves into stone ware jars, which have not been glazed with lead.— The cabbage furnishes the green vegetable matter. which, with the acid, is absorbed by the pickles.— The jars ought to be kept in a moderate tempera- ture. Pickles made iu this manner, neither contain lead nor copper. A small portion of alum will not injure the pickles; but, on the contrary, make them more firm. The addition of alum it is known increases the acid- ity of vinegar, and is frequently added by fraudulem vinegar-makers. But its detection is easy, as will be shown in the following article. Alum contains ( 76 ) nothing deleterious; and, therefore, in the prepara- tion of pickles, for the reason already given, a small portion may be added with advantage. The detection of copper in pickles may be accom- plished by mincing a piece, and putting it into a phial with diluted water of ammonia; if the minutest quan- tity of copper be present, the ammonia will assume a blue colour. If a portion of this blue solution (am- moniaret of copper.) be mixed with a solution of ar- senious acid, a yellowish green arsenite of copper (ScheeWs green,) will be precipitated. If lead be suspected, the pickle may be macerated in aqueous sulphuretted hydrogen. PREPARATION AND ADULTERATION OF VINEGAR. Vinegar is the product of the acetous fermenta- tion,* and is composed of acetic acid, water, and * Notwithstanding vinegar is the product ofthe acetous fer- mentation, there is one remarkable exception, which is men- tioned by Fourcroy and Vauquelin, namely, that when the glut- en of wheat is fermented and mixed with sugar, the liquor is converted into vinegar without fermentation, without efferves- cence, and without the contact of air. This phenomina has not been explained. We may remark here, that acetic acid is developed with other substances by the spontaneous decompo- sition of perine, and by the action of concentrated|sulphuric acid on vegetable substances. The destructive distillation of sugar, gum, weod, &c. also produces it, and, as it is generated by fire, more or less empyreumatic, &c. it was distinguished by the names of pyromucous and pyroligneous acids. See Wood Vin egar. ( 77 ) more or less mucilaginous and colouring matter, from which it is separated by distillation. The distilla- lation should be conducted in glass retorts, if we wish to have the distilled vinegar pure ; because, if we employ a common still, with a pewter worm, it is apt to contract some of the lead, as the pewter of which it is made (ley-pewter) contains more than a fifth part of its weight of lead. When vinegar is distilled, the temperature ought not to exceed that of boiling water, and two thirds or five sixths at most, drawn off. The residuum is still an acid liquid. The product is acetic acid diluted with water. Mr. Chenevix has shown, that it still contains a peculiar mucilaginous and extractive mat- ter, and traces ofa spiritous liquor. The specific quantity of vinegar varies from 1. 0135 to 1. 0251. The strength of vinegar, whether cider, wine, or malt vinegar, depends entirely on the quantity of acetic acid it contains; and may be ascertained by knowing the quantity of alkali or earth, a fluid ounce, or any given quantity, will saturate. This will form a standard of comparison. One ounce, by measure, should dissolve atleast 13 grains of white marble. Mr. Phillips, (Pharm. Lond. p. 7,) states, that English malt vinegar, sp. gr. 1.0204, when distilled, should dissolve carbonate of lime as follows : a fluid ounce (1.8047 cub. in.) of the first eighth which comes over, sp. gr. 0.99712, from 4.5 to 5 grains; ♦he next six eights, sp. gr. 1.0023, should dissolve 7* ( 78 j 8.12 grains of the precipitated carbonate of lime; anti fluid ounee of acid, sp. gr. 1.007 dissolve from 15 to 16 grains precipitated carbonate of lime, or 13.8 grains of marble. • The purified wood vinegar, which is also used for culinary purposes, has usually a specific gravity of about 1.009, which is said to be equivalent to good wine or malt vrfiegar of 1.014. It contains 19-20ths of water, and l-r20th of absolute acetic acid. In England a duty of 4d. is levied on every gallon of vinegar of the above strength. The acetometer, a kind of hydrometer, is used for the purpose. In a large manufactory of malt vinegar, a consider- able revenue is derived from the sale of yeast. Dr. Thatcher, in his Dispensatory, observes, that :'besides pure acetous acid, vinegar contains tartare- ous acid, tartrate of potash, mucilaginous matter, and sometimes phosphoric acid." The existence of the tartareousacid, and of tartrite potash, in some vinegar, maybe detected, as in the wine and gooseberry vinegar; but they do not con- stitute essentially a part of vinegar, neither are they found in cider or malt vinegar. Vinegar, however, is liable to decomposition; but Scheele found that if it be boiled for a few minutes, il may be kept a long time without alteration ; hence it is usually boiled, filtered, and bottled for preservation. In consequence of its antiquity, as it is mentioned by Moses, and was in common use among the eastern nations, the art of preparing it was known at an early period. Vinegar is the result of the acetous fermentation ; the conditions accessary for which, are saccharine i 79 ) .nid mucilaginous matter, with perhaps gluten, a due degree of heat, and exposure of the fluid to air.__ \ Thus beer, ale, &ic. undergo this change, and form vinegar. Cider, which furnishes the best, is also subject to it; and wine, it is known, produces a co- lourless vinegar. The vinous fermentation usually precedes the afce- loils ; and the latter invariably follows when the quantity of alcohol is small, and the proportion of mucilage and extractive matter considerable.— The principal objert of using hops, besides impart- ing a bitter tasle to beer, is to preserve it from the acetous fermentation; and the quantity of hops, for , that reason, is increased for summer ale or beer. In i the vinous fermentation there is a large quantity of oarbonic acid gas generated, during the formation of alcohol; in the acetous, oxygen is absorbed, which combines with carbon and hydrogen in due proportions, and forms acetic acid. This acid, thus generated, is diluted with water, and mixed with re- dundant mucilaginous and other substances. According to Cadet, if 1 part of sugar be dissolved in 7 parts of water, and fermented with yeast in a proper temperature, an excellent vinegar will be formed; but if the sugar exceed an eighth part, the whole is not decomposed. Ueidre we notice the adulteration of vinegar, some remarks concerning some of its preparations may be important. There is a very useful preparation of vinegar, which is very agreeable as a beverage in the summer season, by mixing an ounce or two of it vitha glass of water. This preparation is the sirup (■ 80 ) of vinegar. It is made by boiling two pounds of su- gar in four or five quarts of vinegar down to a sirup. It is nearly equal to the sirup of lime juice, and, in point of cheapnesses recommended as an economical and at the same time a healthy drink. With a por- tion of brandy, it makes a punch little inferior to that prepared with lemon juice or sirup. In garrisons and on board of ships, sirup of vinegar should always be kept. A preparation of vinegar, called aromatic spirit of vinegar, was invented by Mr. Henry, of Manchester, England. The pungent smelling salt is of a similar nature. It is not the sal volatile ammo- nia, usually called smelling salts, but merely sulphate of potash impregnated with acetic acid or radical vinegar. The acetic acid ofthe apothecaries, which contains a little camphor, or fragrant essential oil, and composed fully of one of part of water and two parts of crystallized acid, has a specific gravity of about 1.0/0. The aromatic vinegar of Henry, is no- thing more than concentrated vinegar combined with aromatics. Many attempts, it appears, have been made to imiatate this vinegar. In the London Monthly Magazine, 1812, the following methods are given : Put acetate of copper (distilled verdigrease) into a retort, pour sulphuric acid upon it, apply heat, and collect the acetic acid. When scented with an aro- matic oil, it furnishes ,the preparation of Henry.— Acetic acid may also be formed by distilling acetate of lead with sulphuric acid, in the same manner. But the author of the communication in the Magazine, assures us, that he has formed it extemporaneously ( «1 ) hy putting a portion of acetate of potash (sal diureU icus,) into a smelling bottle, adding gradually half its weight of sulphuric acid, and afterwards a drop or lwo of the essence of bergamot, or oil of lavender. This aromatic vinegar is said, by its pungent odour, to afford relief in head aches and faintings ; and is peculiarly grateful and refreshing in crowded rooms, and in the apartments of the sick. We may remark, also, that there is another preparation called the vin- egar of the four thieves, which is made by infusing sundry aromatic herbs in vinegar; it was used to prevent the effects of contagion. Vinegar may be considerably concentrated by freezing it; the watery part will congeal, and leave the stronger acid. If perfectly dry charcoal be sat- urated with common vinegar, and distilled, water will first come over, which is to be thrown away, and by increasing the heat a very concentrated acid will be obtained. Among the remarkable properties of charcoal, that of producing the discolouration of vinegar may be mentioned. It is found, that if an ounce and a half of charcoal be mixed with a quart of common vinegar, a thick froth will rise to the surface, and in twenty-four hours, it will begin to lose its colour; and in three or four days it will be found, after filtra- tion, to be quite clear and colourless. This process may be advantageously used in the purification of vinegar upon a large scale. Vinegar treated in this manner, will certainly keep longer, without becoming mouldy and vapid. ( 82 ) Acrid vegetables are sometimes infused in vinegar, with the intention of making it appear stronger; but the pungency and taste of vinegar, thus treated, will be found to depend on acrimony more than acidity. But with the view of giving it more acidity, in a cheap manner, some vinegar makers and retailers have been in the practice of adding sulphuric acid, or a solution ofthe supersulphate of alumina and potash. This fraud may be discovered by the solu- ble salts of barytes. If we pour some of the acetate of barytes into vinegar, thus adulterated, it will pro- duce a white precipitate of sulphate of barytes; which, after being made red hot, will be insoluble in nitric acid. The detection of alumina and potash, if alum had been used, is effected by adding ammo- nia, which will throw down the alumina ; and, to an- olherportion, muriate of platinum, which will also pro- duce a precipitate,—thus indicating the existence of that alkali. Muriatic acid may be known by acetate of silver, producing a precipitate of muriate of silver. If nitric acid is used for the purpose, the detec- tion is not so easy, as we have no immediate re-agent or precipitant, by which it can be identified. Nev- ertheless, it may be detected by saturating the vine- gar with potash, and evaporating it to dryness, and exposing the mass to the action of heat with a por- tion of sulphuric acid, when the well known fumes of nitric acid will be disengaged, recognised by their co- lour and smell. Acetic acid, or pyroacetic acid will also be disengaged. A small portion of the drvmass. i 83 ) insisting of nitrate and acetate of potash, if thrown on ignited coals will deflagrate like salt petre. Ace- late of potash would not produce a detonation, nei- ther would muriate or sulphate of potash, salts that are also formed if the muriatic or sulphuric acid is present; but, on the contrary, a decripitation would be the consequence. In a word, vinegar should neither precipitate ace- tate of barytes, nor acetate of silver; neither water impregnated with sulphuretted hydrogen gas, nor li- quid ammonia ; but should saturate a given quantity of carbonate of lime, as a criterion ofthe proportion of acetic acid which it ought to contain. WOOD VINEGAR. Although vinegar is the result of the acetous fer- ine ntalion, a process which generally follows the vi- nous, and is usually made by exposing certain fluids, as cider, to the action of air under an increased tem- perature, yet a crude vinegar has long been prepar- ed for dyers and calico printers, by the destructive distillation of wood in iron retorts. In the charring of wood in iron cylinders, a practice more generally adopted by gun powaer makers, in order to prepare a more pure and perfect coal, a large quantity of wood . inegar or pyroligneous acid is formed, which is now collertod, and purified for use. The manufacture of wood vinegar is a regular business in Europe; and to no person are we more iudebted than to the late Dr. Boll- man for the process of freeing it from tar. and em- ( 84 ) pyreumatic oil, and rendering it fit for all the purpos- es of common vinegar. It is purified by distillation, combining it with lime, and torrifying the acetate of lime, and lastly, decomposing the calcareous salt (acetate of lime,) by sulphuric acid. A better mode consists in decomposing the acetate of lime by sul- phate of soda, separating the sulphate of lime thus formed by filtration, and after evaporating the acetate of soda to dryness, distilling it with sulphuric acid. The acetic acid may be diluted with water, and re- duced to any required strength. Fourcroy and Vau- quelin having shown, that this acid is merely the acet- ic, contaminated with empyreumatic oil and tar, it is obvious that its purification depends on the separa- tion of these substances, when it approaches to ordi- nary vinegar. Wood vinegar possesses many advan- tages over the ordinary kind. It may be kept in a more concentrated state, and diluted as occasion re- quires. It possesses a property which is peculiar to it, namely, that of preventing the putrifaction of ani- mal substances, a property discovered by Mr. Monge. It is hardly necessary to mention, that, for the pre- servation of meat, it has already been extensively used. It is sufficient to plunge meat for a few mo- ments into this acid, even slightly empyreumatic, to preserve it for any length of time. This effect is at- tributed to the presence of empyreumatic oil; and the preservation of meat, fish, he. by smoking, is on the same principle. The presence of sulphuric acid, alum, he. may be detected in the same manner as in common vine- ( 85 ) »ar. Concentrated wood vinegar is particularly cal- culated to take to sea. In consequence of its con- centration, it is more portable, and may be diluted when required. Parry, in his voyage to the north pole, found it particularly useful. Although wood vinegar is considered a recent dis- covery, yet it appears (Jour. Royal Instit. no. 16,) that it was known as early as 1661, and its property of converting minium into sugar of lead. On the principle that meat is cured by smoking, which depends on the action of pyroligneous acid, which is disengaged by the slow and imperfect com- bustion of the fuel; we are informed (Bui. d'En- cour. Aug. 1821,) that meat, after it has been salted, may be preserved by dipping it into an aqueous in- fusion of wood soot. Three pounds of beef require a pound of soot. This quantity is put into half a gallon of water, and macerated for 24 hours. It is then decanted. In this infusion the meat remains half an hour, and is then removed, and dried in the air. It is found that a pound of soot will strongly impregnate two quarts of water, and that the water is charged with l-25th of its weight of acid, of the soot. ADULTERATION OF MILK AND CREAM Cream, we are told, is frequently adulterated with rice powder, or arrow root. The latter when boiled with milk, and the compound added to cream dilut- ( 86 )• ed with milk, is said to impart a richness without materially impairing the taste of the cream. Two hundred and twenty to two hundred and thir- ty grains of arrow root, when mixed with one pint of milk in this manner, and the solution added to three times its quantity of cream, will produce a compound which many prefer to cream alone. But the fraud, when it is used as such, may be detected by adding a solution of iodine to a portion of the suspected cream; if it contain that fecula, it will produce a dark blue colour.* The presence of chalk in milk may be discovered by the tests for lime and carbon- ic acid : chalk, however, will not be held in solution, but merely suspended. Adding water to milk is a common practice with the dealers in that article, the detection of which is difficult. The quantity of curd furnished respective- ly by pure milk, and watered milk, may indicate the proportion of water; for the diminution in the pro- portion of curd in the latter, instance, will be accord- ing to the degree of dilution, admitting that milk is uniform in the quantity of curd it contains. The in- strument called the lactometer, we are told, is calcu- lated to determine the proportion of curd and whey in milk; but we have not seen the instrument, and therefore can say nothing as to the fact. The detec- * Iodine and starch are tests for each other. Iodine produces with it an ioduret, or iodide of starch. Water containing mere- ly one grain ofiodine to the quart, will instantly acquire a blue colour by the addition ofa small portion of starch paste. Stareh will thus indicate 1-450,000th part ofiodine. ( 87 ) tion of water in milk has been attempted by freezing it, a method lately recommended in a newspaper ; and some have advised the use of the hydrometer, believing that pure milk is much heavier than diluted or watered milk. Neither of these trials can be de- pended upon, for the following reason: the boiling and freezing points of milk are nearly the same as those of water, but they vary a few degrees in different milks, and although milk is specifically heavier than water, the precise degree cannot be ascertained, as it seems from some experiments that every particu- lar milk has a specific gravity peculiar to itself* Pure cream is ofa yellow colour, and its consis- tence increases by exposure to the atmosphere. If the exposure is for any considerable time, it will have no longer the flavour of cream, but of very fat cheese ; it is then in fact, cream cheese. Cream possesses many ofthe properties of an oil. It is specifically lighter than water, has an unc lions feel, and stains clothes precisely in the same manner as oil. It is neither soluble in alcohol noi oils. It is composed of a peculiar oil, curd, and se urn; the first is wed known by the name of butter. winch is separated by the operation of churning. It is said that cream may be preserved for many months by boiling it with sugar, in the proportion of one pint to an ounce, keeping it at the same time secluded from the air. The Corstorphon cream, so called by the inhabi- tants of Mid-Lothian, from a village of that name, is said to b^> an agreeable preparation of cream, and ( 88 ) sold in Edinburgh by the name of sweet cream. The process is as follows :— Take skimmed milk that has only acquired a mod- erately acid taste; put it in an upright wooden ves- sel, (an upright churn is commonly used) having a spicket and fosset at the bottom : place that in a tub, and pour hot water into the tub till it rises nearly as high as the milk in the containing vessel. Cover the whole with a cloth to keep in the heat. In a few hours the milk separates into two parts; the upper part assuming the consistence of thick cream, that has very much the appearance of good cream, only moderately acid; the other portion that remains is a thin watery liquid, which is of a pungent acid taste, and may be easily let off by means of a spicket; this liquid is called wigg. The cream is then fit for use. Speaking of this preparation, Dr. Mease, (Archives of Discoveries, vol. iii. p. 269,) remarks that, "No one would believe that it did not consist wholly of real cream that had stood till it became acid. Much of the goodness of this, however, depends upon the skill of the maker; as it is greatly affected by vari- ous circumstances, particularly the degree of heat to which it is subjected, and the acidity of the milk, It is eaten with sugar as a great delicacy." HONEY. The most anciently used and one of the most grateful of all the saccharine juices, is a natural com- pound, according to Mr. Cavezzali, of sugar, muci- ■: 89 ) iage, and an acid. ■ The sugar may be obtained by melting the honey, adding carbonate of lime in pow- der as long as any effervescence appears, and scum- mine the solution while hot. The liquid on stand- ing will gradually deposite crystals of sugar. It is said the sugar is analogous to that of grapes. Mr. Proust observes, that there are two kinds of honey i one always liquid, and the other solid, and not deliquescent. They may be separated he says, by means of alcohol. If Mr. Seguin's experiments are correct, honey must also contain albumen, since substances, which are susceptible of fermentation without yeast, seem, in his opinion, to owe it to then albumen. The clarified honey is nothing more than honey liquified, and separated from its serum. Yristaeus, a pupil of Chiron, is said to have firsi gathered this vegetable juice collected by the bee from various plants, and deposited in the cells of its comb. The honey bee is the apis mellfica of Lin- neaeus. The honey which separates without ex- pression, contains a less proportion of wax, and is of a thick consistence, a white colour, and of a more pleasant taste. The colour and flavour of honey, however, depends on the plants which the bees pre- fer. The honey of young bees, when obtained with- out expression, is called virgin honey; but the ho- ney of old bees pressed from the wax is yellow.* *Th« best sort of French virgin honey, is that of Languedoc, called honey of Narbonne. It should be. thick, granulated, of a clear transparent white colour, of a soft somewhat aromatic smell, and of a sweet and lively taste. If it is very pure, and a> ( 90 ) Several circumstances contribute to the goodness of honey. Where the bee hives are fixed, aromatic plants, particularly thyme, lavender, violets, primro- ses, baum, sage, and borage should abound. It ought to be observed, that all lioney is not wholesome. Bees indiscriminately sip the flowers of all plants which abound with sweet matter, whether it be from innocent flowers, or those actually noxious. As some of these plants are of a poisonous nature, it follows that the honey must partake of their injurious quali- ties. The late professor Barton has written an ex- cellent paper on the subject, in the Transactions oj the American Philosophical Society, vol. v. Poison- ous honey is very common in the West Indies ; but we seldom find our honey of this quality. The plants affording this poisonous honey, are the dwarf laurel, (kalmia angustifolia,) the great laurel, (kalmia latifolia,) the broad leaved moor wort, (an- dromeda marina,) and the kal hisuta, a little shrub most as hard as sugar-candy ; and what renders it so superior, are the many aromatic flowers which grow in those parts, and from which the bees gather their honey. ' It is observed that ho- ney made in mountainous countries is more highly flavoured man that of low grounds. Vanden Heuvel, (Silliman's Journal, m. 84,) speaks of the South American and West Indian honey ; and of the " ardent sun of the tropics, which generates in all vegetable bodies an in- creased portion of saccharine matter, which decks the woods and groves with an endless display of blossoms and flowers, of aromatic and nectareous .fragrance, and distils from the trees of •he forest in luxious streams those balmy juices with which it surcharges them, furnishes a region where bees may luxuriate 'n a unlderness of sweets.'" ( 91 ) •>f the southern states. Dr. Barton is of opinion, that it will be found that other plants yield unwhole- some honey ; such as the Pennsylvania mountain laurel,(Rhododendon maximum,) the wild honey suck- le, (azalea nudiflora,) and the common James-stown weed, (datura stramonium.) The four first plants ought to be extirpated in the neighbourhood of the bee hives ; and the honey procured from the three enumerated in the second place as suspicious, should be carefully examined, to determine the fact with re- gard to them. The goodness of honey for culinary purposes is generally determined by the delicacy of flavour, but the comparative quantities of sugar, and other chem- ical differences have not been much examined. Owing to the abundant quantity of sugar and mu- cilage, in the composition of honey, added to the presence of albumen, according to Seguin ; when honey is mixed with water, it readily undergoes the vinous fermentation, and produces the well known beverage called hydromel, or mead. Thirty-six ounces of honey, and four quarts of warm water, pro- duced a mead by fermentation, which gave Newman 8 ounces of strong alcohol. On this principle honey improves cider. Several experiments have been made on the clar- ification he. of honey, by Mr. Lowitz and others, which cannot be interesting to us at this time; but with regard to the acetification of honey, or convert- ing it into vinegar, it may be useful, perhaps, to add, 'hat by making a mixture of honey and water, in the ( 92 ) proportion of about one part of the former to eight. of the latter, and allowing it to pass through the ace tous fermentation, a white vinegar will be formed, which in many respects is superior to the ordinary vinegar. Honey is often adulterated with flour, which may be detected by diffusing it in blood warm water, by which all the honey will be dissolved, and the flour remain nearly unaltered, and a subsequent boiling of the residue will convert the flour into thick paste. Good honey has usually a solid, or a soft, consist- ence, and is ofa pale yellow colour, with an agreea- ble aromatic flavour. We may observe, that the ancients applied honey to various uses. The most celebrated was the ho- ney of Hybla. They used this honey as a delicacy, although sometimes they fermented it for beverage. Hydromel, or mead, appears to have been a very an- cient drink; and if well prepared, is undoubtedly pleasant and wholesome, and in summer, particular- ly grateful, owing to the large quantity of carbonic acid gas, which it contains. This, however, depends on the time of bottling, and some other minutse, which can only be acquired by practice. Professor Beckman, (History of Inventions, vol. ii, p. 49,) observes, that the practice of putting dead bodies in honey, for the purpose of securing them from putrifaction, is very ancient, and was used at an early period by the Assyrians. The body of Agesipolis, king of Sparta, who died in Macedonia, was sent home in honey, as were also the bodies of I 93 ; Agesilaus, and Aristobulus. The faithless Cleomenea caused the head of Archonides to be put in honey, and had it always placed near him when he was de- liberating upon any affair of great importance, in or- der to fulfil the oaths he had made to undertake no- thing without consulting his head. According to some authors, the body of Alexander the Great, was depos- ited in koney, though it is generally believed it waji embalmed according to the manner ofthe Egyptians. The body of the emperor Justin ii, was placed in honey mixed with spices. Democritus desired to be buried in honey. Besides the use of honey in this manner, it was often applied in ancient times to pur- poses for which we use sugar ; and also, for the pre- servation of fruit, the celebrated purple dye, sundry worms and insects, and other natural curiosities, such as the hippocentaur. In later times it has also been employed for the same purpog^, as is proved, in the opinion of Beckman, by the account given by Alex- ander ab Alexandro, respecting the supposed mer- men. It may appear remarkable, that so long ago as the time of Solon, bee-hives were regulated by certain laws- Solon made a law, that " whosoever placeth a hive of bees, should observe the distance of thirty feet from those that were before placed by his neigh" bour." NUTMEGS. Nutmeg is the produce ofthe myristica officinalis, j>r moschata. It is said to have been known to the ( 94 ) ancients, and to have been the comacum of Theo- phrastus. Nutmegs, preserved entire, are introduced in India with tea, but the mace and pulp are only eaten : the nut is thrown away. Newman procured from 1920 parts, 480 of spiritous, and 280 of watery extract, with 320 of oil. The last two were insipid. By distillation with water, nutmegs yield nearly one tenth of their weight of a. limpid essential oil. On the surface ofthe remaining liquor an unctous con- crete, like tallow, swims, of a white colour, nearly insipid, but used as a basis for odoriferous balsams. Alcohol takes up the whole smell and taste, and as- sumes a bright yellow colour. When the genuine nutmeg is heated, and strongly pressed, it gives out a fluid yellow, oil, whichconcretes on growing cold. A counterfeit nutmeg has/been prepared, composed of oil cake and oil of mace, made into the shape, &c. rif the real. But the fraud is readily-detected by merely cutting it, as the difference in x-ppearance will be at once obvious. It miey be also examined by boiling it; it will fall to pieces, whereas the gen- uine will remain whole. We have heard, indeed, of counterfeit wooden nutmegs, made so artfully out of solid wood, coloured and scented, as to defy de- tection by the eye ; but the labour and pains requir- ed in cutting the wood, would not, it appears to me, recompense the counterfeitPi ! Mace, which constitutes one of the coverings of the nutmeg, furnishes an oil. Nutmegs, we remarked, heated and, strongly pressed, will give out a fluid oil, which concretes into a sebaceoum ( 95 ) consistence; this is the genuine oil of mace; but in the shops, there are generally three sorts.— The best, brought from the East lidies in stonejars,. is sottish, of a yellowish colour, an agreeable fra- grance, greatly resembling that of the nutmeg itself. but of the colour of mace. The next, from Holland. in solid masses, ofa paler colour, having a weakei smell, and inferior to that of India. The last is alto- gether an adulteration, or rather, counterfeit; com- posed ol suet or palm oil, flavoured with a little of the genuine oil of nutmeg. The expressed oil contains both the solid and vc latilo oil ofthe nutmeg. POISON Oil* CONFECTIONARY. The art of the confectioner is employed in many different operations. Although in the preparationof cake, creams, jellys, &c. we have little reason to expect fraudulent adulterations, and especially the addition of deleterious substances, knowing them to be such ; yet instances have occurred, through neg- ligence, where copper has gained admission, in con- sequence, no doubt, of the vessels made use of not having been properly cleansed. All acid fruits, ae v\eil as sebaceous substances, should never be pre- pared in copper vessels ; pies, for instance, made with crust containing a large quantity of butter, as equal parts of flour and butter, a proportion frequent- ly list d for short crust, when baked in pans of that description, must contract a portion of metal.— ( 96 ) Cranberry, and other acid fruit, stewed in copper pans, have been known to produce colics, he. ■ The use of sundry colouring substances for cakes, plums, he. is common. It is observed, that sugar plums, which consist entirely of sugar and starch, are frequently adulterated in England with pipe clay ; a fraud which may be readily detected, by dissolving them in water. This addition is harmless, although it is a foreign ingredient in the composition. Red sugar plums are usually coloured with ver- million, which is frequently adulterated with red lead; the blue iceings are generally coloured with Prussian blue ; the green, by employing the juice ofthe buck- thorn berry, which forms the sap green; the yellow, by using infusions of saffron and turmeric ; and, in short, a variety of vegetable and mineral colours are employed. Certain vegetable colours are inert. This is the case with turmeric, saffron, and red-wood, and with the insect called cochineal. But sap green, as well as Prussian blue, are frequently adulterated; the former with some preparation of copper, and the lat- ter, sometimes with indigo. Foreign conserves, such as limes, citrons, plums, he. are frequently em- pregnated with copper. The art of increasing the quantity of ice cream, from a given quantity of cream, or the particular mode of preparing milk in lieu of cream, and of aug- menting the quantity of jelly from calves'feet by the use of inferior fish glue, he. is known to, and fre- quently practised by, the confectioner. Thus, by ( 97 ) using boiled milk, with occasionally the addition of sugar, a rich milk is formed, which, when frozen, has all the characters of the genuine ice cream. The different kinds of cream, as the vanilla, lemon, straw- berry, he. are formed by extracting from these sub- stances the flavour, colour, he. either by previous digestion, or expression, according to circumstances. The freezing of the cream depends on a well known principle, that of the abstraction of free caloric by means of ice and common salt, a freezing mixture used in such cases. Alihoe.gh, as we remarked, few instances have oc- curred of the wilful introduction of deleterious sub- stances into pies or pastry, yet instances are recorded in which arsenic itself was sprinkled over desserts. Morgagne informs us, that an Italian feast the des- sert was purposely sprinkled over with arsenic ins- tead "of flour. Those of the guests who had previ- ously ate and drank little speedily perished; those who had their sto nachs well filled, were saved by vomiting. He also mentions the case of three chil- dren, who ate a vegetable soup poisoned with arse- nic. The detection of arsenic will be considered when we treat of mineral poisons. Secret poisons were frequently given to guests even at private entertainments. Beckman, in his His- tory of Inventions, says, " that Pope Alexander VI, died in the year 1503, and Cassar Borgia recovered without any loss of health, though, by the bottle's be- 9 v 98 ) ing changed by mistake, he drank ofthe poison that had been prepared for the other guests alone." POISONOUS FISH. Very frequently fish partake of a poisonous quali- ty, and with some constitutions what is inoffensive, is to others decidedly deleterious. In warm climates we meet with fish possessed ofthe most deleterious quality. The barracuda, (perea major,) king fish, (xiphias,) cavallee, (scamber,) rock fish, (perca mari- na,) smooth bottle fish, (ostracion glabellum,) and yellow sprat, are the fish most to be apprehended. The poisonous virus is so great in the latter, that it has been known in several instances to destroy life in half an hour, by exciting dreadful convulsions.— The Conger eel and some other fish, particularly of the shell kind, that feed on the leaves ofthe machin- eel-tree, are also frequently poisonous, and produc- tive of violent cholera. The cause ofthe deleterious quality offish, in all cases, is uncertain; sbme suppose the fi?h even to be a different species ; others, that it is owing to their food; and some, again, attribute the poison to the existence of copper banks, on which they feed. It is supposed that the poison lies in the intestinal tube of the fish, and is assimilated with its food, and cir- culates without any detriment to the fish. Certain and rapid death has been produced by eating the yellow bill sprat. It is necessary at all times to re- lieve the patient by an emetic, either of tartar emetic ( 99 ) or sulphate of zinc, using copious diluent draughts, and spiritous cordials, or even brandy and water. It has been observed, that those who have taken a quan- tity of rum or brandy after eating fish of this nature, have suffered considerably less than those who neg- lected that precaution. Fish forms a great part of the diet of the inhabit- ants of the West Indies, where they are most fre- quently deleterious. To be able to distinguish those of a poisonous nature from such as are wholesome, the surest criterion is to give the entrails to a dog or cat, andif after an hour or two no disorder arises, the fish may be eaten with safety. A method much practised is, to put a silver spoon sometime into the water in which the fish is boiling, and if, upon tak- ing out the spoon it appears unsullied, the fish is sup- posed to be safe; but if the colour be at all changed, it is then judged unwholesome. This test, it is very justly remarked, should never be depended upon.— Fishermen assure us, that fish that have no scales are most apt to prove poisonous. The mytilus edu- lis or muscle, is said to feed occasionally on a dele- terious insect. The conger-eel, he, are deprived of their rankness by washing and salting. The poisonous effects of muscles, lobsters, he. may be obviated by taking a smart emetic, which should be administered as quickly as possible, and afterwards the patient may take the acetous acid, and also milk. The subject of antidotes, in connection with that of poisons, we purpose to consider in our lecture on the detection of mujeral poisons. ( ioo ) POISONOUS CATSUP. Catsup, from the manner it is frequently prepared, is often contaminated with copper. In London, Mr. Accum assures us, that catsup is often nothing else than the residue left after the distillation of vinegar, mixed with a decoction of the outer green husk of the walnut, and seasoned with allspice, he. The presence of copper may be detected by ad- ding to a portion ofthe catsup some liquid ammonia. We will have occasion to mention hereafter mush- room catsup. In the mean time it may not be amiss to remark, that we consider the tumatos catsup, if properly made, as equal to the mushroom; and there is less liability to accidents in making it with the tu- matos, than with mushrooms, which may have been very old, and probably the introduction of poisonous fungus by mistake. The tumatos catsup is usually prepared by mashing them, and digesting them with salt for some hours; then straining the fluid, and boiling it with sundry ar'omatics, as allspice, cloves. and cinnamon, with or without the addition of vine- gar, according to taste or fancy. As a condiment, this catsup possesses all the qualities of the mush- room or walnut. SUNDRY OTHER POISONS AND ADUL- TERATIONS. The leaves ofthe cherry laurel, prunus lauro-cer- asus, a poisonous plan*, which have the flavour of ( 101 i) peach stones or bitter almonds, have been used in cooking, on account of their flavour.* Custards, puddings, creams, blanc-mange, he. frequently re- ceive their flavour from these leaves. Families have been dangerously poisoned by using the cherry laurel. When the leaves of this plant are dist'dled with water, they form the cherry laurel wa- ter, which is frequently mixed with brandy and oth- er spiritous liquors, to imitate or impart the flavour of noyeau. Cordials are indeed sometimes poison- ous. Noyeau especially, which contains the flavour ofthe peach stone and bitter almond, with that ofthe cherry laurel, and is formed by distilling " a spirit," from these substances, is impregnated with the hy- drocyanic or prussic acid, which exists abundantly in the leaves of several plants, and in the bitter ker- nels of some fruits. Instant death has followed the drinking a single glass of noyeau, supposed to have contained a large quantity of prussic acid. The leaves ofthe peach (amygdalut persica,) ocoasionally employed in cooking, ought to be used with great caution. * The truth is, the pruncus lauro-cerasus, in consequence of containing prussic acid, has been used in the place of the latter in some cases of phthisis pulmonalis. Dr. Oliver, in Sil- liman's Journal, iiip. 184, remarks, that he used the laurel wa- ter with success; but being exhausted ofthe water, he procur- ed some of the leaves of the lauro-cerasus, and made a tincture, which had the same effect as the water, and finally, wishing tc use the efficient principle of the lauro-cerasus, be procured the prussic acid. 9* ( 102 ) Anchovy sauce has been found contaminated with lead. This has occurred in consequence of employ- ing Venetian red, as a colouring, which was adultera- ted with orange red, a preparation of lead. Arme- nian bole, an innocent earth, is however more gene- rally used than Venetian red. Lozenges, comfits, ginger pearls, and other articles of this nature, are often adulterated with pipe clay, which may be detected by simply dissolving them in a large quantity of boiling water. The clay will afterwards subside, and may be known by its becom- ing hard like brick when burnt. Olive oil is frequently deleterious, by being con- taminated with lead, in consequence ofthe oil having been expressed from the olive between leaden plates, or by allowing it to clear in leaden cisterns. The French and Italian olive oil, it is observed, is free from this impregnation. Olive oil is said to be often adulterated with the oil of poppy-seeds, in order to preserve it from rancidity. The method recommen- ded for its detection, is by submitting the oil to the freezing temperature, which will freeze the olive oil. and leave that of the poppy-seeds in a fluid state. The presence of lead may be shown by mixing the suspected oil with water impregnated with sulphur- etted hydrogen gas, which will cause the well known brown colour. See Lecture VI. Mustard when bought in the state of flour, is fre- quently sophisticated, and this is known to be partic- ularly the cas«* with the imported Durham mustard. (• 103 } The adulteration, however, is by no means injurious The Durham mustard is usually a mixture of mus- tard and common wheat flour, with a portion of cay- enne pepper. The fine yellow is given to mustard seed by grinding it with turmeric. Turmeric may be detected by adding to the mustard a few drops of a solution of potash, which will change the bright yellow to a brown. The mustard, which is sold in pots, is made ofthe same materials as the Durham, with the addition of bay salt. We do not know ofa single exception to the adulteration of mustard ; when ground into flour, it is always mixed with corn, rye he. and coloured with turmeric, or some other sub- stance. The plea of excuse is, that the mustard seed will not grind without some addition, either of com or rye, owing to the oil it contains.* L mon or citric acid is frequently adulterated; and sometimes tartaric acid is sold in its place. Le- mon acid is frequently used for domestic purposes. The presence of tartaric acid may be known by ad- ding a solution of muriate of potash ; if it produce a precipitate, (the supertartrate of potash,) its pres- * An acrid property or principle is to be found in many veget- ables. We are unacquainted with the chemieal properties and nature, of many of these vegetables, ortheir products, although it is admitted that some peculiar principle, which has not been exainmed, is the cause of their acridity. Most of the ranunculi, the polygonum hydropiper, mustard, &lc. are well known instan- ces. Tins fact has been remarked, that, on drying, some of them loose their acridity, while in others, as mustard, it remains. W.iter extracts it from the ranunculi; while in mustard, it dis •olves only a very small part, and acquires the tas.teof garlic ( 104 ) ence is shown, if not, the citric acid may be judged pure. A solution of tartrate of potash will produce a precipitate in the same manner, with tartaric acid. There is a supersulphate of potash, flavoured with the oil of lemon, that is sold as concrete lemon acid, which is evidently a fraud. If such articles were sold as substitutes, persons would know what they purchased. CoxwelPs concrete salt of lemons is pure citric acid. The preparation of the essential salt of lemon, or citric acid, is certainly advantageous. Lime or le- mon juice, which contains citric acid united with wa- ter, and mucilaginous matter, is very apt to grow mouldy, and spoil in a short time. Several methods have been recommended for preserving the juice ; as straining it, then boiling and bottling it, or putting the juice and pulp into bottles, and covering the top with olive oil. The juice is supposed to feed upon the pulp* The oil is removed by means of cotton before it is used. Heretofore lime juice put in casks was exported to Europe from the West Indies, but now at the suggestion of Mr. Coxwell, the principal maker of citric acid in London, it is saturated with car- bonate of lime, and the citrate of lime in a dry state is only sent. This citrate of lime, when treated with sul- phuric acid, furnishes pure citric acid, which is en- tirely different from that preparation sold in our shops as concrete lemon acid. We must not con- found this acid with a preparation, usually sold in small boxes, and chiefly employed for the removal of ink stains, and iron moulds, called the essential ( 105 ) alt of lemons, which is nothing more than tlie salt of sorrel, or superoxalate of potash in a pulverized form. We may remark, that citric acid has been found un- mixed with other acids in the following vegetable substances : the juice of oranges and lemons, the berries of the cranberry, the red whortleberry, the bird cherry, the nightshade, and the hip, and in union with lime in the onion.. The proportion of citric acid in the cranberry is considerable. Although it is £aid to be unmixed, yet some experiments have de- tected the tartaric acid, but in a very small propor- tion, It has frequently occurred to me, that as the cranberry grows very abundantly in different parts ofthe United States, it would be an object to pre- pare the citric acid from it. It is only necessary to separate the juice by pressure, and treat it in the same manner as lemon juice, fust with carbonate of lime, to obtain a citrate of lime, then with sulphuric acid to disengage the citric acid. I'ofonous mushrooms have frequently proved fatal. There are several species of these fungi, which are decided deleterious in their effects, and, in general, it requires some knowledge to distinguish them a- part. In preparing catsup from mushrooms, the same care is necessary in selecting them. The morell, (phallus esculentus,) which is a kind of fungus, is employed for thickening and heighten- ing the flavour of sauces and soups. It differs from the common fungus in its figure and structure, but if gathered after having been exposed for some days to wet weather, thev are extremely pernicious. Thf. ( »0G ) truffle, (tuber cibarium) is a watery fungus, without root, found in hilly woods and pastures, which have a sandy and clayey bottom. In England, they are discovered by means of dogs, which are taught to hunt for them by their scent. They are internally of a white colour, and have somewhat the odour of garlic. The common mushroom (agaricus campes- tris,) is in the most common demand. It is a fun- gus which consists ofa white cylindrical stalk, and a convex covey of white or brownish colour, which has beneath an irregular arrangement of gills, pinky when young, but afterwards of a dark liver cofour. When it first appears it is smooth and nearly globu- lar, and in this state is called a button. As an arti- cle of food, mushrooms, we are of opinion, are by no • means Wholesome. The agaricus georgii, the agar- icus procerus, and the agaricus orcades, or the cham- pignons of the Frehcb cooks, have been used for the same purpose as the common mushroom. JErated soda water, which remains any length of - time in the coppers either contracts lead or copper. The former from the tinning, as tin is often adultera- ted with lead, and the latter from the copper, where the tinning has either been imperfect or worn off. Such waters never fail to produce sickness, and pain in the stomach and bowels. The instances, however, have been few. Both lead and copper may be de- tected by the well known reagents. Food has also been poisoned by employing copper and leaden ves- sels. These metals may gain admission into food, either in consequence ofthe action of acids, or of ( 107 ) ,ebaceous substances employed in culinary prepara- tions.* Food cooked in an unclean copper vessel is ex- tremely pernicious. One instance is recorded of three men having been poisoned, and afterwards thir- ty more became ill from the same source, on board the British frigate Cyclops. Another instance is stated where cider and honey were boiled in a brew- ing vessel, the rim of which was capped with lead. All who drank of the cider afterwards were seized with a bowel complaint, and some lingered a few years and died. Sundry acid and sebaceous sub- stances should never be kept in earthen ware vessels, which have been glazed with lead. Such glazing is * With regard to the use of tin vessels in culinary concerns, some interesting remarks have been made by Vauquelin, (Ann. de Chim. xxxii, 243,) concerning the action of vinegar on tin. It is known that tin, or the tinning, contains a little lead, and it was of importance to determine whether the vinegar acted upon tjie tin, and, if it did, whether its action was confined to the tin, or extended to the lead. The result was, that a small portion of tin is dissolved by vin- egar, and that when the quantity of lead exceeded the sixth part of the tin, a small portion of the lead was taken up, but only in that part of the vessel in contact both with the vinegar and air ; so that the presence of air to supply the oxygen, for the oxydizement of the metal previously to its solution, appears to be necessary. It is worthy of remark, that the Etiglish block in, generally speaking, is very pure, and consequently the tin plate, (formed by dipping sheets of iron into melted tin,) must be free of lead, or if it exist at all, the quantity must be exceed- ingly small. But the tin met with on the continent, is so much debased or adulterated by dealers in that article, especially the Dutch, that pewter and tin are considered the same substance. ( 108 ) usually made by the vitrification of Oxyde of lead in contact with siliceous substances. Mini Sallad, as it is called, is prepared in some parts of England, by bruising the mint with large lea- den balls; the consequence of which is, that por- tions of the lead are worn off, and mixes with the mint. Leaden milk pans have been made use of in the place of earthen ware, as it is said they will throw up more cream. This practice is certainly injuri- ous. I have heard, indeed, that pewter pans were used in this country for the same purpose; and a gentleman in the neighborhood of Washington city informed me, that he found a greater increase of cream by using a pan or pot made of zinc, and sup- poses that it was in consequence ofa galvanic effect. Vessels of earthen ware, glazed with lead, are ex- tremely improper for the holding of pickles. For that purpose, in particular, stone ware jars, which have been glazed with salt, are perfectly safe. Lead is frequently introduced into cider, by the custom in some countries of lining the beds of the.ci- der presses with lead. When lead is combined with tin, it is not acted upon by acid so readily as when this alloy is not formed; and some even assert, that tin, in such cases, prevents the oxydizement and consequent solution of the lead.* The water ob- * We mentioned in lecture 1st, that, in the preparation of ci- der wine, by boiling the apple juice in copper vessels, a practice in the west of England, a portion of copper was taken up. Dr. Fotbergill detected it, and made the fact known. We have ( 109 ) tained from the distillation of bitter almonds, as well as cherry stones, and peach and laurel leaves, is strongly impregnated with the noxious matter, which gives them their taste and flavour. This water, we remarked, contains prussic acid, which is readily re- cognized. Bitter almonds, peach kernels, &c. should be used with caution. Arrowroot, a fecula or starch prepared from the maranta arundinacea, which is used as a nutricious aliment, is frequently adulterated with starch, particularly that obtained from the sola- rium tuberosum, and sometimes with powdered rice. It is difficult to detect these substances, as the che- mical characters of fecula, (and rice contains as much as seven eighths,) are the same. They are merely adulterations, and partake of nothing ofa de- leterious nature.* remarked in the Artist's Manuel, article cider, that although cider is a cooling, pleasant, and wholesome liquor, during the heat of summer, yet when it is new and tart, and kept in leaden vessels, or passed through leaden pipes, some lead will be taken up, and render it unwholesome; and that such cider cannot fail sooner or later, to produce painful and dangerous colics, and x train of evils, which we have already noticed in treating of water kept in leaden cisterns, and of wine adulterated with su- gar of lead, as the effect alluded to, is owing to the presence of the same metal. *Potatoe starch, which is prepared by pouring cold water on potatoes grated down to a pulp, and placed in a fine searce, pos- sesses all the essential characters of starch. It is said, however, to go much farther than common starch, and possesses a very perceptible crystallised appearance; it is also heavier. It can- not be employed with the same advantage for hair powder.— See Hair poioder. According to Eiahof, the potatoe, or root of the solanum tv 10 ( no ) Artificial asses milk is used for similar purposes as the foregoing. It is prepared of eryngo root and li- quorice root boiled in water, to which new milk is added, and the whole boiled and strained. The fe- cula obtained from the Palma Japonica or the In- dian bread tree, called sago, is a nutritive and light • .aliment; potatoe starch has frequently been mixed, and granulated with it. The root of the bitter cassa- da is poisonous when raw, but when deprived of its noxious qualities, which resides in the juice, by heat, forms a wholesome and nutritive bread. This bread is also made from the sweet cassada. Cassadawhen fermented with molasses and potatoes, is said to form a strong intoxicating liquor, called ouycou. The fluid expressed from this root contains a very fine fecula or starch, which is used in the preparation of the delicate dishes. The tapioca, another substance of a very nourishing character, is said to be made from the cassada by heating it over the fire, to sepa- rate the poisonous principle, and treating it after- wards in the usual manner for separating fecula. Sundry marmalades, we may observe, frequently contain slight impregnation of copper and lead from berosum, when dried by a moderate heat, will be reduced to l-4th of its original weight, and yields in every hundred parts 15 of starch, with seven of fibrous starchy matter. Potatoes loose by boiling 1 to 1 1-2 per cent, of their weight; and it is found, that, by boiling, the albumen, fibrous matter, and starch, unite together, and form an insoluble compound. Potatoes contain no gluten, in which respect they differ from sundry grains, as wheat, &.c. and hence will not make raised bread without the addition of wheat or rye, which imparts it. ( 111 ) the vessels in which they are made. Thus the fruit of the mammcea Americane, or Toddy tree, is prepar- ed into a marmalade with sugar and spice^, and is an article of that kind. PORTABLE SOUP. Portable soup is frequently adulterated, that is to say, instead of forming it altogether of the gelatinous parts of mutton, veal, and beef; fish glue, and even beef glue, are added to it. The fraud cannot well be detected, because the chemical properties of gelatin, no matter from what animal substance it is obtained, are the same. Portable soup is a dry substance, prepared by boiling calves' feet, legs of beef, knuck- les of veal, and legs of mutton, in certain proportions, separating the fatty matter which rises; and after clarifying it with the white of eggs, (adding salt, &;c. as seasoning,) boiling the whole to the consistence of very thick paste, which is then poured out to cool, and becomes solid. Half an ounce will make a pint of liquid soup. A process for extracting gelatin from bones, as practised in Paris, which is said to be very econom- ical, is given in the American Journal of Science i, p. 170. The head, legs, ribs, he. are first broken, but kept as compact as possible, and put to soak in a mixture of muriatic icid and water. The muriatic acid used, bears about 23 deg. ofthe aerometer, and is diluted by water to about 6 deg. Four parts of the liquor are used to one part of bones. The bones are ( 112 ) suffered to digest for six or eight days; the phos- phate of lime is taken up, and the gelatinous part re- mains. This, having the original shape of the bone. is then taken out and drained, and immersed a short time in boiling water, to separate any fat and acid which might remain. It is then wiped, and after- wards washed in copious streams of warm water, to whiten it, and render it more transparent. It is then dried in the shade. The authqr of the communication states, that 2 ounces of this gelatin are equal to 3 lbs. of beef, in making soup, and of as good a quality as six pounds of beef. It is constantly used in some of the hospi- tals of Paris. Soup of any kind should never be boiled in cop- per vessels, for the obvious reason, that the fatty matter, which it contains, will act upon, and take up a portion of the copper. An additional quantity of nutriment may be imparted, by boiling with the soup beef bones, previously bruised. They contain a large quantity of gelatin. A very cheap and econom- ical soup is prepared with bones. By digesting them first* in a Papin's digester, mixing them with ordina- ry soup, and boiling them together, a large quantity of gelatin is imparted, and the soup rendered remark- ably rich. If this practice were adopted at our pub- lic soup houses, the economy would be great, and the soup in every respect improved. Proust obtained from powdered bones, about l-16th of their weight of gelatin. The remarks of this eminent chemist concerning the advantage of C 113 ) powdered bones in the preparation of soup, are con- clusive. Cadet de Vaux has shown, that from bones thus powdered, as much good soup may be obtained, as from five times their weight of meat. But this is supposed to be exaggerated, since Dr. Young repeat- ed the experiment without the same success. The component parts of bones are chiefly four; viz. earthy salts> principally phosphate of lime, fat, gelat'n, and cartilage. The proportion of the first, and also or the fat, is variable ; but Mr. Proust ob- tained in one experiment, one fourth of the weight of fat of the bones employed. The cartilage, or soft white elastic substance';/ remains after the bones are deprived of their fat and gelatin by boiling,and of their earthy salts, by digesting them in diluted acids. It retains the figure of the bones. Hatchett observes, that it has the properties of coagulated albumen.— The cartilage, it will be observed, is the portion of the bone first formed, and the requisite degree of hardness is afterwards given by phosphate of lime; but the gelatin and fat, particularly the first, give the requisite degree of toughness and strength. Bone, deprived of them, becomes brittle. Potatoes, when steamed and dried, have been used in France in the preparation of soup, under the name of polenta. At Manlius, 550 persons reduced to want, were fed during 18 months, at the rate of Iwo centimes and a half (about l-40th of a cent,) per day, with a soup prepared entirely of this substance. Suppose this polenta were joined with the gelatin oi 10* ( 114 ) bones, would not the aliment thus produced be worthy of public attention, since so many indigent families may be supplied at so comparatively trifling an expense ? The establishment of soup houses are eminently useful. Dr. Lind, in his Treatise to prevent the want of provisions at sea, a circumstance highly necessary to be attended to, assures us, that two pounds of port- able soup, and the same of salep, will afford a whole- some diet for a person for a month. Salep is pow- dered orchis root. The flour of sweet potatoes, or of the common potatoe, or the latter root, sliced and thoroughly baked, similar to the French polenta* would answer as well. The animal substance peculiar to muscular flesh, which gives odour an'd flavour to soup or broth, is called by Mr. Tenard, osmazome. Whether it is in reality a distinct substance, or merely fibrin, is not as yet determined; it differs, however, from gelatin. Its proportion to the latter, in flesh, is about one to five. Four pounds of muscular flesh, bruised and washed with cold water, produces nearly six drachms of this substance. It has a brownish yellow colour. It is soluble both in water and alcohol. The aque- ous solution does not gelatinize ; but when evaporat- ed, leaves the osmazome in the state of a brown mat- ter. It is supposed that osmazome is nothing more thau fibrin, slightly altered by being boiled in water, and dissolved in that liquid. Its identity with •fibrin; however, is not established, ( 115 ) WHITE BUTTER. CASEOUS BUTTER. It is a fact but little known, or attended to, that ca- seous butter is often imposed upon buyers, as pure butter; alledging that its whiteness is owing to the cream of which it is made. Butter, it is true, is not always of that delicate yellow colour, which frequent- ly depends on the food, fodder, or pasturage of cows ; but the introduction of curd into butter, in preparing it for the market, is a practice which has been fol- lowed by butter-hucksters in our large cities, for the purpose of increasing its quantity. Butter of this description, has neither the taste, flavour, nor co- lour of good butter. It is usually white, and has a a cheesy taste. It appears more or less milky, indi- cating that it has not been worked in the same man- ner as pure butter. The " working over" of butter, especially if rancid, by churning it with cream, is ne- vertheless a frequent, and necessary operation. It renders it sweet, and at the same time increases its quantity. In order, however,to increase the quantity of butter, we have seen it recommended, to add to the cream, in the act of churning, a portion of alum dis- solved in water; the acid of which, it is apparent, separates the curd along with the butter. Butter, thus prepared, cannot be pure. The fraudulent practice of sophisticating butter with curd is perform- ed by merely mixing it with the butter. The curd is obtained from milk in the usual manner by rennet. The deception may be detected by merely melting •he butter. Pure butter will melt, and flow like oil; ( tie ) and sophisticated butter will become milky and tur- bid. When butter is melted, which contains curd, the latter will gradually precipitate; whereas the pure butter will remain fluid. The mixture, however, will assume a milky appearance. The curd may be separated by a fine flannel filter, and even its quan- tity ascertained.* * Lagrange (Chemistry ii, 983;) observes, that if butter be put into a glass, and then exposed to heat, three parts are separated from it; one butyraceous and yellow,.one serous, and one ca- seous. The presence ofthe two last, however, depends entire- ly upon circumstances. If the butter is imperfectly worked*. caseous and serous substances may be found in it ; but when butter is thoroughly worked, and prepared from sweet cream,. and without the addition of acid, no indications of caseous ma- ter, or at least in a very small degree, will be observed. The water, however, usually found in butter,is not to be confound- ed altogether, with serum. It is a fact, nevertheless, that but little butter is so perfectly made as to be entirely free from some cheesy matter, by reason ofthe cream becoming slightly ace- sant, or the presence of acid in the act of churning, which sep- arates in the same manner as rennet the caseous matter or eurd. As milk, is separated into three substances, cream, curd, and whey; the first differs from the second and third in containing a peculiar oil, or butler,.but combined with curd and some se- rum, which in the operation of churning separates into two por- tions, one of which is fluid, and takes the name of butter-milk, and, from the experiments of Parmentier and Deyeux, possess- es the properties of milk deprived of cream; the second, or curd differs essentially from butter and whey, and according to Ber- zelius, constitutes but 3 1-2 per cent, of cream, and is used in the making of cheese; the third, or whey, according to the same chemist, constitutes 92 per cent, of cream, and is very com- { 117 ) The caseous part of milk and cream, possesses characters entirely distinct from those of butter, or whey. It has many of the properties of coagulated albumen. In a dry state, when all the moisture is squeezed out, it possesses a considerable degree of brittlcncss. When curd is precipitated by rennet, or by acid, as the muriatic or sulphuric, it is found to be com- bined with a portion of the acid. In the Dutch cheese, for instance, where the curd has been sepa- rated by spirit of sea salt, (muriatic acid,) the acid communicates a sharp taste. If the precipitate ob- tained by the addition of acid be digested over car- bonate of lime, it will be decomposed ; the acid will unite with the lime, and the curd will be dissolved in the water. In this manner an aqueous solution of curd, having a yellow colour, and resembling a solution of gum, may be obtained. The mineral acids form with curd analogous compounds to albu- men and fibrin. These remarks, however, are in- tended to show, that, after we separate the curd from the butter, with which it is fraudulently contamina- pound in its nature, consisting of lactic acid, sugar of milk, and saline m.ittei, chiefly phosphates. For remarks concern- ing card, see the article on Ciiecse. Whatever opinion may be given on the constitution of butter; viz. that it contains card ami serum in variable proportions, it it is a fact that those win understand the making of butter, pre- pare it free from these substances, or, if they exist at all, they arc, as were marked, in a comparatively small proportion. Any One inn satisfy himself of this fact by subniif.iiig the butter to fusion, and comparing various specimens in that way. ( 118 ) ted, we may identify, by experiment, the existenct of that substance. In many parts of England, they colour their but- ter in winter, to make it appear like May butter.— The best English butter is made in the county of Essex, known by the name of Epping butter. Sometimes butter is adulterated with lard, but this sophistication is readily discoverable by the taste. By saponifying it, however, with potash, we might detect both the margaric and oleic acids, which are known to exist in lard, or to be formed in the act of saponification. It may not be improper to offer some general re- marks respecting the preservation of butter. The common mode of preserving butter is by the addition of salt; but the most effectual method, in the opinion of Dr. Parr, is to use two drachms of su- gar, as much salt petre, with half an ounce of salt to every pound. Dr. Anderson recommends a similar mixture; viz. one part of sugar, one of salt petre, two of common salt; which is to be mixed thorough- ly with the butter, after it is freed from the milk, in the proportion of one ounce to sixteen. The butter is to be pressed tight. The taste of butter, thus pre- pared, is said at first to be unpleasant; but in a fort- night, it becomes of a rich flavour. Mr. Eaton, (Survey of the Turkish Empire.) as- sures us, that most of the butter used at' Constanti- nople, is kept sweet by melting it while fresh over a a very slow fire, and removing the scum as it forms. This effect depends also upon the separation of the ( 119 ) r aseous matter; for Mr. Thenard approves of the method, and observes, that the melting should be done on a water bath, or at a heat not exceeding 180 deg. F. and be continued till all the caseous mat- ter has subsided to the bottom, which is to be sep- arated by a strainer. He recommends also cooling it, by immersing the vessel containing it in a mix- ture of pounded ice and salt, or very cold spring wa- ter, otherwise it will become lumpy, and not resist the action of air so effectually. If kept in a close vessel, and in a cool place, it will keep a length of time. How far Mr. Thenard's conclusion is correct, as to the quantity of cheesy matter in fresh butter, is doubtful; for, he remarks, that if this preserved but- ter be beaten up with one sixth of its weight of cheesy matter when used, it will resemble fresh butter. In France, the proportion of caseous matter in butter, from their mode of preparation, may be a sixth part of the whole butter; but this proportion, admitting the fact, is far too great for our best butter. No fin- er butter is made than in this county, (Orange,) and in Goshen ; it melts and flows like oil, without giving hardly any signs of curd ; and none, generally speak- ing, is so free of rancidity. This is, likewise, the character of the best Pennsylvania butter; but the butter of the south, from some cause or other, is usu- ally white, has little or no flavour, and contains, we would judge, an undue proportion of caseous mat- ter. The taste of rancid butter may be much corrected ( 120 ; by melting and cooling it. Mi. Eaton further re- marks, that, by melting butter in the Tartarian me- thod, and salting it after the English custom, he kept it good and fine tasted for two years, without im- pairing its taste and colour. That the rancidity of butter depends, in a great measure, upon its retaining some whey and caseous matter, there can be no doubt; and that butter keeps in proportion as it is free from them, either by working it, in the usual way, or melting it as before stated, appears to be the fact. To prevent the actu- al decomposition of the caseous and fluid part, in the imperfectly made butter, and also any change which the butter itself might undergo, in causing ran- cidity, the use of sugar, nitre, salt, he. seems to b< predicated. Fourcroy is of opinion, that, whatever pains be taken, the butter will still retain a portion of curd; and we are told, that to melt butter without granula- tions, flour is added to prevent the cheesy portion falling to the bottom. This effect takes place only with caseous butter. With respect to the colour, Parmentier and Dey- eux have remarked, that different colours may be im- parted to butter, by the juice of carrots, alkanet root, violets, he. The May butter, rose butter, he. are imitated by artificial colouring matter. LARD AND TALLOW. Tallow, or suet, differs from hog's lard in con- sistence ; the former is brittle, and the latter is sofi ( 121 ) and sometimes semi-fluid. They are acted upon by the strong acids, which gradually decompose them. When nitric acid is digested on fat, the acid parts with some of its oxygen, and according to Fourcroy, produces an oxyde of fat of a yellow colour. At 400 deg. fat begins to emit a smoke; then, as the heat increases, it becomes blackish ; and, finally, an abundance of carburetted hydrogen and carbonic acid passes off. Without noticing at this time, the substances found in fat, viz. stearin and elain, which by saponification, are converted into the two acids just mentioned, the margaric and oleic, it will be suf- ficient to observe, that the presence of suet or tal- low in hog's lard, an adulteration often met with, is readily recognised by the physical character of the lard : if it is pure, it will have a soft feel, and in sum- mer a semi-fluid appearance, more or less translu- cent, and devoid of a yellow tinge; but if mixed with tallow, it will be more hard, and have an opaque look, and generally a yellow tinge. CAPERS. Capers are the unopened flower buds of a low shrub, the capparis spinosa, which grows from the crevices of rocks and walls, and among rubbish, in the southern parts of France and Italy, and the Le- vant. The buds are picked, and put into vinegar and salt. When a sufficient quantity of them is col- lected, they are distributed according to their size, into different vessels, again put mto vinegar, and then 11 ( 1*2 ) packed up for exportation. If they are suspected to be greened by copper, macerating them in liquid ammonia will determine it, by producing a blue col- our. The flower buds of the marsh marigold, (caltha palustris,) and nasturtiums, are frequently pickled.- and eaten as a substitute for capers. SOY. This is a kind of sauce prepared from the dolichot soya or soja, by allowing it to undergo a spontaneous fermentation. In the memoirs of the Swedish acad- emy, its preparation is particularly described. The proportions are fifty pounds ofthe bean, fifty pounde of salt, sixty pounds of wheat flour, and two hun- dred and fifty pounds of water. We gave an account of this substance in the Artisfs Manual, from, which we make the following extracts : After having well washed the beans, they are boiled in well water in an open vessel for some hours, or until they have become soft, as to be worked be- tween the fingers. They are then taken out, and put into large shallow wooden vessels. In these they are spread out to the depth of two inches, and when they are cold, the wheat flour is gradually thrown in, and mixed with the beans. The whole being well mixed, the mass is spread abroad in the vessels beforementioned. When it be- gins to grow mouldy, and heat is disengaged, whicli happens after two or three days, the cover is raised, in order that the air may have free access. ( 123 ) During this time a rancid odour exhales : and il the mass become green, it is a sign that the whole goes on properly; but if it begins to be black, which must be carefully noticed, the lid must be raised high- er. If it once becomes black, the whole is spoiled. As soon as all the surface is covered with green mouldiness, which usually happens in eight or ten days, the cover is taken off, and the compound is ex- posed to the sun and air for several days. When it has become hard, it is cut into small fragments, which are thrown into an earthen vessel, upon which the water, having the salt first dissolved in it, is poured. The vessel thus filled is placed in the sun, and its contents stirred up regularly every morning and eve- ning ; and a cover is put on at night to defend it from the cold, as well as to prevent any rain from finding entrance. The hotter the sun, the sooner will the s©y he completed. A? the mass diminishes by evaporation, well wa- ter is added ; and this digestion is continued, till the salt water has entirely dissolved the flour and the beans. The vessel is still left for some days in the sun, iu order to complete the solution still more ef- fectually, as the good quality ofthe soy depends up- on this circumstance ; and the daily stirring or agita- tion is continued. When at length the mass has become very succu- lent and oily, the whole as well the thick as the more fluid portions, is poured into bags, through which the »oy is pressed, and is then clear and ready for use. ( 124 ) It is to be kept in bottles well corked. The Chinese, who deal in this article, keep it in large pitchers well closed. Before it is strained in the press, the soy is of a deep brown colour, but afterwards it becomes black. The Chinese also prepare two kinds of soy from the dregs which remain. For the first kind they add one hundred and fifty pounds, and thirty pounds of salt, and after having pressed the mass, they ag^in add one hundred pounds of water, and twenty pounds of salt, always proceeding as before described. The two last kinds of soy are not strong, but very salt, more especially the latter, which is also lighter coloured. These two kinds are the most common in China, and are used both by natives and Europe- ans. The differences of price are as 8, 4 and 1. The soy prepared, as we have mentioned, is suc- culent, oily, moderately soft, and entirely different from the spurious kind usually sold in Europe. As to taste it is equal to that of Japan, which is general- ly considered the best. Mr. Ekeberg asserts that the soy is boiled, and sugar, ginger and other spices are added; but this is an error, since spy has no taste either of sugar or spices, for the prevailing taste is that of salt. Dr. Mease (Archives of Useful Knowledge, vol. i. p. 219,) assures us, that the bean, dolichos soya, bears the climate ol Pennsylvania well: " there is therefore nothing" he adds, " to prevent our enjoy- ing the agreeable condiment, of which it is the basis, except our own indifference." Why has it not been cultivated ? ( '25 ) We have been particular in noticing the Oh>n*»se aiethod of preparing soy, a sauce much used in Eu- rope, as well as in the East Indies; and although we have given it more attention than at first view its im- portance would seem to require, yet as its mode of preparation is but little known, these remarks may not be altogether unacceptable- It is obvious that the goodness of soy depends on the fermentation of the bean assisted by the flour ; that the salt water combines with the flour and beans, although altered by fermentation ; that the heat of the sun assists the solution, and the mass becomes succulent and oily before it is finished ; and that the perfection of the sauce depends on the complete combination of the whole materials. The colour of soy is first brown, but becomes black by age. The presence of deleterious substances, if suspec- ted, such as copper, lead, &c. may be known by the usual reagents. It should have nothing of a rank putrescent taste, and when thrown on burning coals give no decided smell similar to burning bones; if so, gelatin, in all probability, has been added to it. VERMACELLI. There is a farinaceous preparation sold by con- fectioners, called Vermacelli, which, although not a- dulterated to the best of our knowledge, is neverthe- less liable to contain copper from the copper vessels, •fee. which are sometimes used in its manufacture 11* ' t 126 ) Vermacelli is used in soup. It is composed, oi ought to be, of flour, cheese, yolk of egg, and sugar, coloured yellow either by turmeric root or saffron. Vermacelli, in appearance, resembles a conjeries of worms; hence its name. It is also made into slender pieces, or cylindrical bits. This shape ie given to the composition* by forcing it with a piston through a number of hqles, the diameter of which corresponds therewith. It is an elegant addition to a family soup. The detection of copper, if it be sus- pected, (and this indeed may very seldom be the case,) may be effected by dissolving it in water and adding liquid ammonia, or by putting some of it in a phial and pouring liquid ammonia upon it. Besides Vermacelli, their is a preparation of flour and eggs, called macaroni, which is used in soups. It is chiefly imported from Italy. Its name implies cut-paste. If blanched almonds are used in the pre- paration of macaroni, care ought to be taken to em- ploy the freshest The bitter almonds should be a- foided. DISTILLED WATERS. Distilled waters are sometimes liable to adultera- tion. These waters are prepared by distilling plants, or certain parts of plants, with water; they commu- nicate an aromatic flavour, in consequence of their essential oil. Sundry waters are now prepared more expeditiously, by combining the essential oil with vater. This is effected by the intervention of sugar ( 127 ) and. alcohol. Thus, a few drops of the oil of mint may be united with, and make a pint or more of mint water. The distillers make use of blossoms or flowers for two reasons; viz. either to obtain colouring matter, as from violets, or aromatic oil, as from mint, rose- mary, lavender, he. Sundry fruits are also used by the distiller. Thus quinces, when fermented and distilled, produces a spiritous water,frequently made use ol for ratifia ; and cherries, plums, apricots, kernels of nuts, he. are employed for the same purpose. Some of which we shall show are decidedly deleterious. The most common -waters are those of mint and peppermint, clove, lemon, citron, orange flower, rose, lavender, cinnamon, pennyroyal, he. Water which has been made by distillation, and which con- sists of nothing more than an impregnation of the es- sential oil, may be distinguished from the water pre- pared by using sugar and alcohol, or spirit, with es- sential oil, by submitting it to evaporation. It will evaporate entirely, without leaving a residue; in the other case, owing to the sugar, a residue will be left of a sirupy consistence and taste. The only deleterious waters to be apprehended, are those obtained by the distillation of the peach blossoms, lauro-cerasus, and bitter kernels, which, we have said, contain prussic acid, and impart it to water by distillation. Since Mr. Scheele pointed out the method of obtaining hydrocyanic acid in a separate state, the similarity between its smell and the ( 128 ) odour of bitter almonds, peach blossoms, and othet vegetable substances, did not fail to be remaiked.— In 1802, Bohn mixed the distilled water of bitter al- monds with potash, and added it to a solution of iron, which gave a blue precipitate, a fact conclusive of the existence of prussic acid. The distilled water of peach blossom, and of lauro-cerasus, treated in the same manner, or mixed with lime water, and then with a solution of sulphate of iron, gave Mr. Schro- der the same indications of prussic acid. These facts were confirmed by the experiments of Gehlen, Bucholz, and Vatiquelin. Bucholz found it in the essential oil of bitter almonds, and Vatiquelin in the distilled water ofthe kernels of apricots, and it has since been discovered in the flowers of the sloe, (prunus spinosa,) and the leaves of the bay leaved willow, (salix pentandra.) It cannot be doubted that almost all the bitter tasted kernels con- tain this acid. See Hydrocyanic acid. If, however, it be suspected in the distilled water of vegetables, especially of such leaves as have a peculiar sweet smell, or of kernels, the fact may be known by mix- ing it with some lime water, or weak solution of pot- ash, and adding to the mixture a solution of iron. Hydrocyanic acid is incompatible with some ol the proximate principles of vegetables; and hence we do not find it in a number of essential oils in daily use. The rose leaf contains no traces of it- We shall have occasion to observe, hereafter, when we speak of certain active poisons, that too much care cannot be used in preventing the accidental admix- ture of leaves, he. containing this acid. ( ^9 , it is a fact that almost every plant, distinguished by a peculiar odour, contains a volatile oil, to which it is indebted for that odour. Fixed oils are only found in the seeds of plants, and are almost entirely confined to those which have two cotyledons; as al- monds, linseed, poppy seed, he. whereas volatile oils are discovered in every part of plants except the cotyledons of the seeds, where they never occur.— Besides the leaves and flower, it is, therefore, to be found in the root, stem, and rind or pulp ofthe fruit. Distillation is the usual process for extracting es- sential oils, but they may be obtained in some in- stances, like fixed oils, by expression. Water, when distilled from an aromatic or odoril erous plant or flower, contains a mere impregnation ofthe essential oil or aroma, and that which is found floating on the surface is always removed for use.— The water itself has neither a turbid, nor milky ap- pearance, which is the case with the extemporaneous preparation to which we have alluded. This turbid- ness, however, may be removed by filtration. SUGAR.* The refining of sugar by using lime water, bul- lock's blood, or eggs, and claying in the usual man- * Su^u possesses some remarkable chemical properties. It i.s capable of combining with, and neutralizing both acids and alkaline bodies. It is decomposed by sulphuric and muriatic .k id, and nitric ,icid convert^ it into oxalic and malic acid*.— One hundred parts of sugar, will yield fifty-eight parts of oxalic ( 130 ) ner, purifies it from all extraneous matter. A smalt portion of lime, of acetate of lime, and of alumina, derived from the clay, may occasionally be found in >t. According to a more modern process, sulphate of zinc is also used, four ounces of which are added to every hundred lbs. of sugar. The lime water decom- acid. Chlorine converts it into malic acid, and changes, at the same time, into muriatic acid. Sugar increases the solubility of lime and strontion, and forms a combination with them.— The fixed alkalies, also, combine with sugar, but the saccharine taste is destroyed. It may be restored, however, by the addi- tion of sulphuric acid, which unites with the alkali. The sul- phate of potash, or soda, thus formed, may be separated by al- cohol. If lime has a tendency, like potash or soda, to destroy the sweet principle of sugar, might not sulphuric acid be employed with advantage in restoring it? The union of sugar with me- tallic oxydes, &c. forms saccharates. Thus we have the sac- charate of lead, formed by digesting oxyde of lead in a solution of sugar. The juice of the sugar cane, it will be recollected, has been recommended as an antidote to arsenic; and sugar, in substance, has been used with decided success, as an antidote against the poisonous effects of copper. JVo doubt, in both in- stances, the effect is owing to a combination of the sugar with the metallic oxydes, neutralising them so as to become harmless^ especially with the oxyde of copper. These are the principal properties of sugar. Sugar is obtained in the West Indies, and some parts ofthe United States, from the arundo saccharifera or sugar cane. It is also plentifully obtained from the sap or juice of a tree very Common in this country, the acer saccharinum or sugar maple. It has been extracted, also, from the beet. There are different species of sugar, designated by the name of sugar of figs, sugar of grapes, starch sugar, Botany bay sugar, mushroom sugar. manna, &,c. A variety ot plants are found to «,oiitain sugar. ( 131 ) poses the sulphate of zinc, and forms sulphate of lime, and the oxyde of zinc combines with the extractive matter, tannin, and galic acid. These new com- pounds are insoluble, and are separated by filtration. If the quantity of sulphate of zinc should be too great, and not be decomposed, it will remain in, and mix will), the sugar. In that case, it may be detect- ed by dissolving the sugar in the water, and using the tests for .'-tiljihuric acid and zinc. When the sugar is hssoWed, the alumina will separate. Grocers have been known to mix different sub- stances with brown.sugar, for the purpose of increas- ing its weight. Sand, dried clay, powdered gypsum, Indian meal, Sic. have been used for that purpose. But these sophistications are readily known by the appearance of the sugar, and its solution in water. Pure sue,ar should dissolve wholly in water, and ioivo a clear solution, without leaving any sediment, the nature of which, if any, may be determined by experiment.* The quantity of water added to su- z;ar. with the same view of increasing its weight, may be shown, by exposing a certain portion to the ac- * Sugar i.-, very soluble in water. According to Wenzel. water, at the temperature of 48 deg. dissolves its own weight of our modern, and more powerful metallic poi- ( 144 ) sons, the ancients were not acquainted. Tophaniu. who resided at Palermo, prepared drops called aqua Tophania, which, it seems, were remarkably pow- erful. She distributed her poison, according to La- bat, (Travels through Italy, iv, 33,) in small glass phials, with this inscription; " Manna of St. Nich- olas of Bare," and ornamented with the image ol the saint. In 1659, at Rome, secret poisons were greatly in use, and in 1670, in France, the subject excited more than usual attention. It appears a young man by the name of Godin de Sainte Croix, had acquired the secret while in prison, from Exili, an Italian, and had communicated it to the Marchio- ness de Brinvillier; of whom it was said, that she fill- ed the church yards more rapidly than by the usual course of disease! There is no doubt that the poison employed by the Marchioness, was ofa metallic nature; for, if we mistake not, in the casket which was found, and open- ed, both corosive sublimate and arsenic were disco- vered. The water hemlock (cicuta aquatica,) is the plant which was chiefly used in ancient Greece, to destroy the lives of all who were condemned to death. It is said to have been an ingredient in the medicine of Thrasyas of Mantinea, and combined with the juice of poppies, which killed without pain.* * Mr. Wilmer, in his Observations on Poisonous Vegetables, has noticed the effect ofthe aquatic hemlock. He considers it one ofthe most active ofthe vegetables poison?- Early in the ( 145 ) t nder the name of secret poisons, all those poi- sons were considered, which, while they were ad- ministered imperceptibly,gradually shortened[life like a lingering disease. The Greeks and Romans wire celebrated for such poisons. According to Plutarch3 Q ii itilian, and other respectable authorities, a slow poison was administered to Aratus ol Sic^on. Ai one time, when Aratus spit up blood, he .exclaimed. " This is the effect of royal friendship!" These poisons, however, were ofthe vegetable kind. Such were the infamous practices of those days! spring, when it grows in the water, cows often eat of it, and ate killed by it. Mr. Wihner observes, that the poison produces epileptic symptoms. Dr. Parr, quoting Wepfer as authority, observes, that some children, who, on eating the roots of this phint, Were -ei/.ed with pains in the precordia, loss of speech, abolition of tin senses, and terrible convulsions; the jaws «ere locked, blood started from the ears, the eyes were distorted, and some of them died in half an hour. Others have observed that the old roots are a more active and sudden poison than arsenic or cor- rosive sublimate. We do not know the precise nature of the vegetable poisons; but, from some late experiments of Dr. Brande, it would ap- pear they existed in an alkali ofa distinct kind. The poison ofthe deadly nightshade, however, is supposed to reside in an oil. The new vegetable alkali obtained from the henbane, called by the doctor, %o«aamt',which possesses the characteristic properties of alkali, is to be used with caution; for Dr. (Ac. in Ins edition of Nicholson's Chemical Dictionary, observes, that " the examination of the alkaline constituents of narcotic plants, demands great circumspection, because in them the whole poisonous proporties of the plant are concentrated.— The vapour is particularly prejudicial to the eyes. The small- est morsel put upon the tongue, is rery dangerous." 13 ( H6 ) The Upas, the celebrated poison tree of Java, is now known to be fabulous; and, according to Fonta- na, the ticuna is much less virulent than it has been represented.* Poisons operate differently, with greater or less energy, on different constitutions. Like the tyrant of antiquity, who used himself to all kinds of poison^ that he might be proof against their attack, some may feed on what would be destructive to others; hence the old proverb, " what is one's meat is another's poi- son." "x Dr. Horsfield who wrote, in the Batavian Transaction*. on the Upas, observes, that the account published by Foersrli respecting the situation of the poison tree, its effect on the sur- rounding country, &tc. is an extravagant forgery. The exig- ence of a tree in Java, from the sap of which, a poison, equal in fatality, when thown into the circulation, to the strongest poi- sons heretofore known, is confirmed by the doctor. The tree, however, which produces this poison is the anchor, and grows in the eastern extremity of the island. Rhumphius gives a loii£ account of the Upas, under the name of arbor toxicaria. " Be sides the true poison tree," says the Rev. Mr. Clarke, " the Upas ofthe Eastern Islands, and the anchar ofthe Javans, this island produces a shrub, which, as far as observations have hitherto been made, is peculiar to the same, and, by a different mode of preparation, furnishes a poison far exceeding the Upas in violence. Its name is chetik, &lcA The anchar is one of the largest trees in the forests of Java, and furnishes a milky juice from which the celebrated poison it prepared. The bark is said to possess singular properties, \\ hich is prepared also in a particular manner. But the juice, from which the JaVans prepare the poison, produces a mortal effect when introduced into the body by pointed weapons. Its pre- paration is an exclusive art of the inhabitants of the eastern e\ tremity of the island. ( 147 ) This immunity is, however, limited. No consti- tution can be proof against the effect of poison. By tracing their symptoms, and their progress, and by even detecting the poison in the stomach ofthe vic- tims, no poisoner can now escape with impunity. It may be interesting, and perhaps useful to you to be informed, that animals, in many respects, are singularly exempt fcom the effect of a number of sub- stances decidedly deleterious to man. We do not vouch for the truth, but we are informed by some writers, (Parr. .Me/I. Die.) that a horse can take a drachm of arsenic daily1; and improve in his coat and condition. Nux vomica is not peculiarly dangerous to man, except in considerable doses, though it soon de- stroys brutes. The aloes is a poison to dogs and foxes. The cocculus indicus is deleterious to fish, and yet is an ingredient in British porter. The phellandrium aquaticum is fatal to horses, and innox- ious to oxen. The dornicum fattens antelopes. thrushes, and swallows, but is fatal to dogs. Pep- per is injurious to swine, and parsley seeds to birds. Bitter almonds destroy foxes, cats, and chickens.— V.irious poisonous berries are eaten by certain birds. which, although innoxious to them, render their flesh poisonous, and unfit to be eaten. This happens at certain seasons, and mostly with the pheasant kind The seeds of hemlock are eaten without injury by some bird-, of stramonium by pheasants, ofthe Col- tium temidentum by jays, and the roots of henbane by pi loo < 148 ; Thus again, to insects of every kind, except tilt tinea?, camphor is fatal; frogs inclosed in a vessel with camphor, experience strong convulsions; and with sparrows and other birds, according to Meng- hini and Carminati, the effects are variahle ; while a few grains would be fatal to birds ; cats, and other small quadrupeds, were seldom killed by less than a scruple. Dogs appear hydrophobic with less than two drachms. For the destruction of moths in wool- en cloths, fur, he. camphor has been used with success, and especially when joined with tobacco leaves. Antimony was at one time considered innocent to brutes, but fatal.to man. Basil Valentine, who was at the head of a college of monks, having observed that this mineral fattened pigs, imagined it would have the same effect on the holy brotherhood ; but the case was seriously different. The unfortunate fathers, who made use of it, died in a very short time, and the mineral was pronounced a poison. Hence the origin of its name, antimoine,—against monks. The opinion that antimony was a poison was en- tertained many years, until experience taught the contrary; in fact, it gave rise to much discussion among medical men, especially in France. The antimony, however, which the unfortunate Valentine gave to his brotherhood, must, we apprehend, have contained arsenic, although in too small a quantity to have any effect on swine. The common antimony sold in the shops, which is used as a medicine for beasts, and particularly for ( 1^9 ) horses in the composition called horse-powder, it may be proper to remark, is a sulphuret of that metal; but when antimony is oxydized, in that state it is more or less pernicious, and when the oxyde is com- bined with tartaric acid and tartrate of potash, itcon- stitutes the salt called tartar emetic. It is with mercury, and many other metals as with antimony ; in its metallic state, it is perfectly inert, but when oxydized, is corrosive and escharotic in the highest degree. If the per oxyde of mercury be combined with chlorine, a very virulent poison (cor- rosive sublimtte,) will be formed. Dr. Parr (L'ond. Med. Die. art. Midicina forensis el politica,) has given some useful remarks on this subject. He considers that poisons may be acci- dental or designed. After mentioning the symptoms when poison has been administered, he observes, that they are violent, inflammatory, stimulants, or seda- tives. The pungent stimulants he ranks among the accidental poisons, the symptoms of which are pain in swallowing, and the inflammation ofthe fauces.— The power of arsenic is shown by violent inflammation and gangrene in the stomach. When the stimulant poisons have been the cause of death, the abdomen is greatly inflated, becomes rapidly putrid, dark spots appear on the body, erosion, inflammation, and gan- grene are found in the fauces and stomach, the blood la black, and collected in the veins; above all, the villous coat ofthe stomach is destroyed. It i? also remarked, that if gangrenous spots should appear in the stomach, after the body has been long buried, IS* ( J 50 ) and these spots surrounded by a reddish circle, these were the effects of changes during life. Should the colour ofthe whole be uniform, the putrefaction took place after death. The Spanish flye (meloc vesicat.) kills by partial stimulus. It produces inflammation, then gangrene. With respect to accidental poisons, they are of two kinds; those received in the food, or swallowed by mistake instead of a medicine. The first are chiefly copper, arsenic, and lead; the latter, nitre. camphor, corrosive alkalies, or the mineral acids. ARSENIC. Arsenic, or ratsbane, as it is commonly called, is by far the most fatal poison, with which we are ac- quainted. That which is sold is the white arsenic, called also the white oxyde of arsenic, but more cor- rectly the arsenious acid. Although arsenious acid is considered an active poison, yetthe arsenic acid is accounted the most violent of the two, occasioning death as well as the arsenious acid, according to Mr. Brodie, by-acting on the brain and the heart. With regard to the reagents for the detection of arsenic, they are numerous; and methods have been devised to determine the existence of arsenic in the dry way. Arsenious acid is soluble in water, and it's degree of solubility is according to the temperature of the water. This solution is acid, as is shown by its ef- fect on certain vegetable blues. With lime water it < 151 ) produces an arsenite of lime, soluble in an excess of the solution. With sulphuretted hydrogen gas, and liydrosulphuretted water, a golden yellow sulphuret >f arsenic is precipitated. This is so delicate a test. that it will detect 1.100000th of arsenious acid in wa- ter. The sulphuret of ammonia, and the hydrosul- phuretand dydroguretted sulphurte of potash, have a similar effect if a drop or two of nitric acid be used ; but they should be employed in connection with other reagents. The observations of Dr. Bostock on the precipitations produced by these tests, are just;— that they produce with tartarised antimony (tartrate of potash and antimony,) and with acids, precipitates of a similar colour, but this fact can be determined by examining the precipitates. It is readily disco- vered whether the precipitate be one of arsenic, one of antimony, or one of sulphur, by merely subjecting it to the action of heat, and recognising the arsenic by its well known garlic smell. If the precipitate or sulphuret of arsenic be dried on a filter, and heated with a portion of caustic pot- ash, a sulphuret of potash will be formed, and at the same time the arsenic will be sublimed in a metallic state, coating the sides ofthe tube. When arsenious acid is combined with potash, that is to say, a solution of potash added to arsenious acid, an arsenite of potash will result, which will produce with a solution of sulphate of copper, a yellowish green precipitate, called Scheele's green. The proportions best suited to produce the arse- nite of cooper, according to Dr. Bostock, are one of ( 152 ) arsenious acid, three of potash, and five of sulphate of copper. Nitrate of silver is also a test for arsenious acid, with which it forms an arsenite of silver, of a yellow colour, which is soluble in an excess of nitric acid. The best mode of applying this test, as it is regard- ed one ofthe best, is by first adding water of ammo- nia, and plunging the end ofa glass rod in it, and then in the supposed arsenious solution; after which we dip another rod into a solution of pure nitrate of sil- ver, and transfer it into an arsenious solution. A fine yellow cloud will be formed, where they come in contact, being the arsenite of silver, and a slight milkiness will also be perceptible. This mode of using the nitrate of silver was recommended by Dr. Marcet. Mr. Hume employs the nitrate of silver dif- ferently. He dissolves about ten grains of lunar caustic in nine or ten times its weight of distilled wa- ter, and precipitates the solution by liquid ammo- nia; and redissolving the precipitate (oxyde of sil- ver,) by an excess of ammonia, he forms a solution of the oxyde of silver in ammonia, with nitrate of ammonia. A rod dipped in it, and applied to a flu- id supposed to contain arsenic, will produce a yellow precipitate if it is present. President Cooper, of South Carolina College, re- commends chromic acid as a test for arsenie; the delicacy of which is so great, that 1.50th part of a grain of arsenic put on a piece of glass, will become decidedly green in three hours with a single drop of a strong solution of chromate of potash. The arse- ( L^ ) nic is said to unite with a part of the oxygeu of tin chromic acid, and the arseniate of potash thus pro- duced, envelopes the green oxyde of chrome. Chro- inate of potash with the arsenical ague drop, produ- ces in a few hours a green colour; with a solution of corrosive sublimate (per chloride of mercury,) an or- ange colour, and with solutions of copper a bright brown colour. Of the cupreous tests, the ammoniaco-sulphate of copper, (ammoniaret of copper,) appears to be pre- ferable. It forms instantly a grass green precipitate, the arsenite of copper, (Seheele's green,) which be- comes brown with sulphuretted hydrogen gas. This is also the case with the precipitate produced with the sulphate of copper. Either the ammoniaco-sul- phate, or the ammoniaco-acetatc of copper will de- tect 1.110000 ofthe weight ofthe arsenic in water. A fact is mentioned in the American Journal of Science iii, 354, by Dr. Porter, that the onion juice with the solution of sulphate of copper, but without carbonate of potash, produces, in a weak arsenical solution, a shade like Seheele's green ; but, if carbo- nate of potash be added, the effect is completely dif- ferent. He mentions also the effect of chroinate of potash on sulphate of copper; for, in the production of Seheele's green by arsenic, sulphate of copper and carbonate of potash, chroinate of potash, he ob- serves, might be substituted for the arsenic ; and that it produced a precipitate not to be distinguished, b} the eye, from Seheele's green ! Professor, now President. Cooper, however, in an ( 154 ) article in the same Journal vol. iv, p. 155, replies to the observations of Dr. Porter, with his usual per- spicuity. He remarks, " that although a greenish colour may be produced by onion juice, and by cof- fee, with a solution of sulphate of copper, it is so dingy and so different from Seheele's green, that the most inexperienced eye need be under no mistake," and "that it is utterly impossible for any chemist to be led away by the ambiguity of colour produced by Dr. Porter's reagents, as a single drop of ammonia will instantaneously detect the copper in all these ex- periments." The professor also remarks, that Dr. Porter's sum- mary is not accurate as a matter of fact. "Take sul- phate of copper," says he, "precipitated by carbon- ate of potash, add chromate of potash in the way you cite the experiment; a green colour will be produ- ced exactly like Seheele's green : so it will if you add infusion of turmeric, gamboge, or saffron, and any other liquor equally yellow with the chromate of pot- ash : but this superinduced yellow colour can be washed away completely, and the carbonate of cop- per will resume its original blue tint; no chromate of copper is found, no chemical action has taken place; the colour is a mere optical deception that can impose upon no chemist. But, if to a strong solution of sulphate of copper, you add an equal quantity of chromate of potash of the strength usu- sttally employed by the manufacturers of chromic yellow, you will produce a green chromate of cop- per, that will retain its colour unchanged by repeat- ( 155. ) •d ablution. Chromate of potash, therefore, cannot lie substituted for arsenic, if the experiment be made is Dr. Porter has directed." The fcrrocyanatc of potash produces with arsenic, a blood red precipitate. If the precipitates, which contain arsenic, be dried, and exposed on an ignited coal, they will give a peculiar smell resembling that ot '.oirlic. If a little of an arsenical solution be pla- eed on glass, and the two wires from a voltaic bat- tery be brought in contact, metallic arsenic will be lormed at the negative pole. If the wire, which con- ducts the galvanic fluid, be copper, it will be whit- ened like tombac, which alloy is actually formed. Some of the salts of iron, as the deuto-acetate, have been used as reagents for the same purpose.* But, notwithstanding all these tests, the most satisfac- tory evidence of the existence of arsenic is derived from its reduction to the metallic state. A small quantitv of the matter suspected to contain arsenic, when mixed with a little dry black flux, and put into a narrow i;!ass tube sealed at one end, and the bot- tom of the tube heated by the blow pipe till red for ■:"1 recommended some years ago, in a paper I think in the Memoirs of the Columbian Chemical Society, the use of some of the salt> of iron a> tests for arsenic. At that time, no writer mentioned the application of the salts of iron for that purpose. did not consider any preparation of iron, as a reagent for arsenic, in any respect decidedly advantageous, since we have so many other tests more decisive, and more to be depended upon. I thought no more of it until the recommendation ofthe deutoacetate of iron brought it to my recollection. ( 150 ) i minute, will give a garlic odour, and the steel lus- fred coating of metallic arsenic will be seen about one fourth of iai inch above the bottom of the tube.— This metallic arsenic may be examined with the re- agoi is before mentioned, or placed between copper plates,and exposed to heat,. Iricb will give them a u bite stain, forming the tombac alloy. If a substance sup- posed to contain oo;--:o :,.: >clxed wiih charcoal, or the black f! iX, jand .posed in the same manner be- tween p.uies.of copotr, they will also indicate it. Dr. Ure informs us, mat tincture of ginger will produce with trie cupreous reagent a green colour; and advi- ses, therefore, the use of several reagents for the de- tection of arsenic. Tea, he remarks, covers arsenic from the same test, but that such poisonous tea be- comes by its addition of an obscure violet, or olive red, scarcely yielding any precipitate. Sulphuret- ted hydrogen throws down a fine yellow sulphuret of arsenic. Orfila, who has written largely on poisons, speaks ofthe various modifications of the precipitates pro- duced by arsenic, when contained in wine, coffee, tea, broth, he. In a case of life and death, and the real existence of arsenic is to be made manifest, without a doubt, the fluid should be evaporated to dryness, and the residue exposed to heat as before mentioned. Brugnatelli has proposed as a test for arsenic, the blue compound of iodine and starch, which changes to a reddish hue with arsenical solu- tions. See Corrosive sublimate. ( 157 ) If the arsenic should be united with oil, boiling the mixture with water, and then separating the oil by the capillary action of cotton wick, may be resorted to. II with resins, they may be taken up by oil of turpentine; for it is found, that alcohol, although a solvent of resins, is also a solvent of arsenious acid. If the arsenic be combined with tea or coffee, it is necessary to separate the tannin, by means of gelat- in, previous to the application ofthe reagents for ar- senic. White arsenic, or arsenious acid, according to Dr. Wollaston, exhibits a very beautiful phenomena when mixed with quick lime, and heated in a glass tube. At a certain temperature the mixture becomes igni- ted, the combustion gradually pervading the whole mass, and metallic arsenic sublimes. It is supposed in this experiment, that the arsenious acid gives out a portion of oxygen to another portion, converting the latter into arsenic acid, which unites with the lime into an arseniate of lime, while at the same time ano- ther portion of the arsenious acid is reduced. This experiment may be made with others to show the identity of arsenic. When arsenic is exposed to the action of the blow pipe, it is dissipated with a garlic smell. Latger pieces, however, when heated on a piece of ignited charcoal, do not produce a smell; to effect.which it must be mixed with powdered charcoal, and reduc- ed. If arsenic is held in solution, it may be recog- nised by dipping into its solution a piece of char- coal, which is afterwards to be dried and ignited: ( 158 ) this experiment, with the methods of discovering ai senic, already mentioned, may be useful. The arsenites are equally poisonous with the un- combined arsenious acid. Mr. Brodie by a num- ber of experiments on rabbits and dogs, established a principle/ as to the operation of arsenic on the liv- ing system, namely, "the suspension of the func- tions ofthe heart and brain, occasioned by the ab- sorption of these substances into the circulation, and their consequent determination to the nervous sys- tem and the alimentary canal." As arsenic mineralizes metals or is combined with certain ores, the smelting of such ores, as well as the working of them, unless great caution be used, is ex- tremely injurious to health. Miners gave to an un- known mineral, which often proved prejudicial to their health, the name of cabalt, derived from calbe- lus, a spirit. This spirit, according to the supersti- tious notions ofthe times, haunted mines, destroyed the labours ofthe miners, and gave them a great deal of unnecessary trouble. Such, however, were the injurious, if not the fatal effects of arsenic to miners, and those who worked the arsenical cobalt ores, that according to Professor Beckman, " it was once cus- tomary to introduce into the church service a pray- er, that God would preserve miners and their works from kobalts and spirits." The ancients, we remarked, were not acquainted with, arsenic; but this fact is certain, that the prin- cipal ingredient of those secret poisons, which, in latter times, were brought to perfection, in France ( 159 ) and Italy, was arsenic. Charles VI. king ofthe two Sicilies, told his physician, Garelli, who communica- ted the same to Dr. Hoffman, in 1719, that the pois- on of Tophania, of infamous memory, was composed of an " arsenical calx dissolved in aqua cymbalaria," and the poison of Exilli, Sainte Croix and the Mar- hionessof Hrinvillier, was also an xarsenical mixture. They were both, in the opinion of Dr. Hahneman, usenical neutral salts, i. e. a preparation of arsenic, farseniate of potash) made by deflagrating nitrate of potash and arsenious acid in a crucible. Dr. Fordyce remarks, in comparing the effects of arsenic and gold, that while the former is poisonous, the latter is a cordial in the pocket, and only a poison to the mind. When oxydized, however, it becomes poisonous ; and the muriate of gold is thus strongly characterised. For antidotes to arsenic, see the following article. CORROSIVE SUBLIMATE. There are two preparations of mercury with chlo- rine, viz. calomel and corrosive sublimate. The former is the submuriate, now called the proto-chlo- ride of mercury, in which the mercury is at the min- im mi of oxydizement; the latter is the corrosive m iriate, or per chloride of mercury, containing in the oxyde a maximum of oxygen. Corrosive sub- limate, next to arsenic, is the most virulent of the metallic pois.v.is. Its presence may be recognized bv several reagents ; if?, portion be exposed to heat 160 ) id a glass tube, it will rise and line the inner surface in the form of a shining white crust. When dissol- ved in water, its solution produces the following phenomena with reagents. If the soliuton be pour- ed into the compound of iodine and starch, it will strike a red colour, the same as arsenic; but if to the arsenical fluid, thus coloured, we add some drops of sulphuric acid, the original blue colour will be re- stored, whereas it will not restore the colour produc- ed by the corrosive sublimate. Chromate of potash produces with corrosive sub- limate a precipitate of an orange colour. Caustie potash put on sublimate, and made to act upon it with heat, will give a red colour, which by gentle ig- nition will disappear, and metallic mercury will rise and line the upper part of the tube. The solution of corrosive sublimate turns sirup of violets to green. The bicarbonates of potash and soda throw down a deep brick red precipitate, which, if heated, will af- ford metallic mercury. Caustic potash gives a yellow precipitate, and lime water produces an or- ange yellow colour. Water of ammonia gives a white precipitate, which changes to yellow by heat. Sulphuretted hydrogen, and hydrosulphurets, pro- duce a black or blackish brown precipitate, which, when strongly heated, is wholly volatilized without any odour of garlic. Dr. Parr says, that the saline mercurials may be discovered by adding ammonia, and heating the whole in a close vessel, when the mercury will be so far revived as to whiten copper on rubbing. r i6i ) To exhibit the mercury in a metallic state by the igency of galvanism, is the method of discovering corrosive sublimate proposed by Mr. Sylvester. If a piece of zinc or iron wire, about three inches long, bent at right angles, the legs of which being distant about the diamele.r of a gold ring, be tied to a ring of that metal; and if a plate of glass, not less than three inches square, be laid as nearly horizontal as possible, and on one side some sulphuric acid dilut- ed with six times its weight of water, spread to the size ofa half penny, be placed, and at a little dis- tance from this towards the other side some of the solution supposed to contain corrosive sublimate, till the edges ofthe two liquids join together; then, when the wire and ring, prepared as above, are laid in such a way that the wire may touch the acid, while the gold ring is in contact with the suspected fluid, if the smallest quantity of corrosive sublimate be pre- sent, the mercury will be reduced and cover the ring on the part which touched the fluid. These are the means usually employed for the detection of corrosive sublimate. It may be useful to know, that in all cases of pois- on, the stomach should be relieved as soon as possi- ble, by means of a strong emetic, drinking freely af- terwards of diluting liquors, such as a decoction of barley with gum arabic, mutton and veal broths, &c. in order to sheathe the parts, and prevent their being acted upon. If arsenic should be the poison, oi!5 butter, and other fatty substances ought not to be ad- ministered, as they are said to dissolve and promote 14* ( 162 ) its action ; but, in their place, mucilaginous and ge- latinous substances must be employed. The sul- phuret of potash, in the proportion of a drachm dis- solved in a pint of water, is a remedy which some writers inform us, will afford great relief in cases of poison both from arsenic and corrosive sublimate. Vinegar is recommended by some authors as an antidote for arsenic, the efficacy of which is denied; milk, is also recommended by Morgagni, and oil of aniseed and ink by Navier. Dr. Chisholm, howev- er, states that the juice of sugar cane is the best anti- dote. Sulphurretted hydrogen water may, on the same principle, be used along with emetics; but of all an- tidotes for corrosive sublimate, the white of eggs, or albumen has the preference. It is to be properly di- luted with water previous to its use. Albumen con- verts the corrosive muriate or per chloride of mer- cury into calomel, or protochloride. Albumen has a very sensible effect on solutions of corrosive sublimate. Dr. Bostock, (JVich. Jour. xiv. 142,J assures us, that if a drop of a saturated solution of corrosive sublimate be added to water containing 1-2000th part of its weight of albumen an evident milkiness will be produced, followed by a curdy pre- cipitate. Corrosive sublimate is considered, there- fore a very delicate test ofthe presence of albumen. The precipitate when dry, contains about S-^ths of its weight of albumen. While none of the earths form insoluble com- pounds with albumen, in which respect they resem- I 1W ) ble the alkalies, the metallic oxydes exhibit a differ- ent character. The effect of albumen on sundry metallic solutions, is detailed by Dr. Thomson, in his System of Chemistry, vol. iv. p. 404, according to his own experiments; some of which we shall no- tice. With nitrate of silver, a copious reddish brown precipitate, not re-dissolved by ammoniu; with ni- trate of mercury, a white precipitate ; with corrosive sublimate, a light white precipitate; with persul- phate of copper, a greenish white precipitate ; with nitrate and acetate of lead, a copious white precipi- tate, he. If, as above remarked, the precipitate ob- tained by adding a solution of corrosive sublimate to albumen, contains 5-7ths of its weight of albumen, the remaining 2-7ths must be the corrosive subli- mate, or rather, according to Dr. Ure, calomel or protochloride of mercury. If this conclusion be cor- rect, the albumen during its solidification or coagu- lation must take a part ofthe oxygen from the oxyde of mercury, thus reducing the per oxyde to the min- imum of oxydizement, a fact which seems reasona- ble, as it is remarked, that albumen during its coag- ulation absorbs oxygen. As albumen possesses some ofthe distinctive characters of gelatin, such as precipitating tannin from its solution, and formin°- a combination therewith,the idea has occurred to me,that gelatin might be also advantageously employed as an antidote to some mineral poisons. I am sensible, nevertheless, that the precipitates produced by ge- latin in some metallic solutions are different from ;bose occasioned by albumen ; as, for instance, that ( 164 ) several metallic oxydes, when agitated in a solution of gelatin deprive it of its water, and that some me- tallic salts, likewise, precipitate gelatin from water. In these respects the effect of gelatin would be dif- ferent from albumen. PREPARATIONS OF COPPER. The acid combinations of copper, and the oxyde*- of copper, are all decidedly virulent, but in a less degree than the preceding. Copper, we have alrea- dy seen, may gain admission into food in a variety of ways. Verdigrease, which is usually formed or some combination of copper with vegetable acids, in culinary concerns, is an active poison. The rea- gents for detecting this metal are several, the princi- pal of which are the following: liquid ammonia, which produces a compound ofa very deep blue, when added in excess to a solution of copper; fer- rocyanate of potash, which is an excellent test, pro- ducing a brown or chocolate coloured precipitate in solutions containing the per oxyde ; chromate of potash, occasioning a precipitate of brown chromate of copper; arsenite of potash, which forms with cu- preous solutions a yellowish green precipitate, the arsenite of copper; the precipitation of metallic copper by a plate of iron; carbonated alkalies, which throw down a green carbonate, soluble with efferves- cence in acids; and hydrosulphuret of ammonia, as well as the hydrosulphurets generally, by lorminga dark brown or black precipitate. ( 165 ) In a medical view, copper supports the doctrine of Linnaeus, that medicine differs from poison, not in quality, but in power. In moderate doses, like oth- er metals it is sedative, tonic, or antispasmodic. We have, however, mentioned the danger of employing vessels for culinary purposes, which contain any proportion of copper in their composition, for the metal is acted upon by acid snd sebacious substan- ces. The danger of employing such vessels has been found by experience, and particularly with the crew ofthe frigate Cyclops, noticed in a preceding lecture; but Mr. Bizard and others, have pointed out the deleterious consequences of using copper u- tensils. When copper or ils preparations is taken in large quantities, the symptoms are described to be " nau- sea, with a constant taste of copper remaining in the back part of the fauces; violent vo*niting; the most dreadful oppression on the breast; the most acute pains of, and a burning heat in the stomach; cold; vertigo; bloody stools; watchfulness, increr'sing to delirium; faintings; convulsions; paralysis; and ap- oplexy ; frequently with eruptions ofthe skin ; some- times resembling lepra." The only chemical antidote to cupreous solutions whose operation is well understood, is water strongly impregnated with sulphuretted hydrogen gas. The alkaline hydrosulphurets, on account of their acridity ought not to be prescribed. We observed, that Dr. Chisholm recommended the juice ofthe sugar cane, as an antidote to arsenic. It is found that sugar, ob- ( 166 ) tained from the juice, is also an antidote to copper, but its mode of action is obscure. Orfila mentions, that persons who had swallowed by accident or inten- tion poisonous doses of acetate of copper, recovered by taking large doses of sugar. What may appear incredible is, that he uniformly found when a quan- tity of verdigrease, sufficient to kill an animal alone in an hour or two, was mixed with sugar, and given to dogs, it proved perfectly harmless. It appears that sugar can neutralize both the the oxydes of lead and copper, producing the neutral saccharates of these metals. When an ounce of white sugar is boiled with ten grains of verdigrease, a green liquid will be formed, which is not affected by the most delicate tests of copper. / There is another antidote to copper, viz. charcoal Charcoal, in fact, has been recommended as a gen- eral antidote for poisons, as well as metallic prepa- rations. Even when other remedies have failed in giving relief, in cases of poison by copper, charcoal powder is said to have been administered with the most beneficial effects. But so far as the experi- ments of Orfila are to be relied upon, the most cer- tain antidote is unquestionably sugar. Some writers affirm, that the encomiums passed upon charcoal as an antidote, are extravagant, and that charcoal can not be altogether depended upon. We know of no set of experiments with charcoal. As an antiseptic, its powers are unquestionable. When copper has been inadvertently swallowed, it is seldom necessary to administer an emetic. -;17 ( 167 ) the vomiting it excites is sufficiently active. Sick- ness and violent pain in the stomach may ensue without vomiting; in that case a few grains of sul- phate of zinc, (white vitriol) may be given. If an e- mctic is not required, medical authors usually recom- mend the administration of mucilaginous substances. and oil, butter, and milk, with an occasional use of alkali. Soap is recommended by some ; and a so- lution of sulphuret of potash (hepar suljihuris,) given with milk or with mucilages. In the modern tables of chemical equivalents we find, that the saccharate of lead is 192; viz. SI, the equivalent number of sugar, and 112 that of oxyde ol lead, but no mention is made of the combination of oxyde copper and sugar. If 72 be the number for the protoxyde of copper, and 81 for that of su- gar, and the combination in those proportions, the saccharate of the protoxyde of copper must be 12. SI. 153 for its equivalent number. Travis, in his .Medical observations and inquiries, ii. 1, remarks, that copper was supposed to be a cause of scurvy at sea, introduced into the system of sailors, by a neglect in cleaning the culinary vessels ofthe ship. This idea, however, is fallacious That it is injurious, in other respects, cannot be denied. See Lecture II. on the use of copper vessels for cul inary purposes. PREPARATIONS OF LEAD. The oxydes and salts of lead are very deleterious. We mentioned when speaking of wine, of the use of (168 ) lead and its acetate in correcting its acescency ; and the practice of adulterating wines with that metal, at differents periods. The ancients knew the action of spoiled or sour wine on lead ; for in order to try their liquor, they usually immersed a plate of lead; if it became corroded, they condemned the wine. Lead produces a particular disease called the poitau colic, (cojica pictonum,) by the inhalation of vapours arising from lead, or the frequent handling of some of its preparations ; hence painter's and glazier's are frequently attacked by it, and especially those who work in the white lead manufactories. The effects of this metal, however small the quantity introduced into the system, is sooner or later fatal. The introduction of lead into cider, we have men- tioned when treating of sundry poisons. When uni- ted with cider, lead is supposed to produce the poi- tau colic. It may be presented to the cider, we re- marked, in the instruments employed in pressing the apples, or added to correct the acidity of cider, in the same manner as wine. Sir G. Baker discovered lead in the Devonshire cider, which occasioned we are told, the poitau or dry cholic; a disease that terminates by nervous spasms, convulsons and death. Lead taken in any quantity is highly deleterious to every animal. It destroys irratibility, and hence occasions in the intestinal canal the disease we have mentioned. On this account its prepara- tions are highly useful in external inflammations, bruises, he. and when administered in proper doses, lessen the irritability of the arterial system, relievp internal hsemorages and spasms. 1 169 ) The vapours of lead from smelting houses are in- jurious. Notwithstanding the colica pictonum is frequently the effect of handling and working in lead, Dr. Parr remarks, that " numerous are the printers, glaziers, and painters, who have never suffered from the sat- urnine colic." The means of preventing this dis- ease, are pointed out by the doctor : when glazier's lead is flattened in a mill, the lead comes out warm, and should be handled in gloves; the printer should wash his hands with soap and water whenever he leaves his work for his meals, and smear them slight- ly with oil when he begins; the painter should have water at hand, and wash offimmediately every atom of paint whicli accidentally falls on it, and each work- man will find fat meat, particularly fat bacon, in a morning, useful, and occasionally, if costive, a dose of castor oil, or two ounces of olive oil may be tak- en. By these simple means, the doctor assures us, he has preserved the health of many, who have been constantly employed in either business, and experi- enced repeated attacks of cholic. In saturnine col- ics, the farmers in Devonshire have used with suc- cess equal parts of brandy and oil of turpentine, as an active stimulus to restore the irratibility. Doctor Parr, however, mentions as a fact, as he »s not disposed to admit all that is said respecting the formation of carbonate of lead in particular instanc- es, the solution of lead in other cases, &c. that he has kept vinegar in a vessel glazed with oxyde of • ead in the usual manner, and could not detect the 15 ( 170 ) the least particle of lead in it! He asserts also that no lead is taken up in the distillation of liquors through leaden pipes, nor in the preparation of oil of vitriol: both of which are contrary to fact. Why do we find sulphate of lead in oil of vitriol ? To counteract the effect of lead on the system, a course of sulphuretted hydrogen or hepatic waters, laxatives of various kinds, sulphur, castor oil, sul- phate of magnesia, and calomel should be resorted to, added to warm sea bathing, and if necessary, a mercurial course. The proper counter poison, for a dangerous dose of sugar of lead, is a solution of Ep- som or Glauber's salt, for the obvious reason, that they immediately decompose the acetate of lead, and forra an insoluble sulphate of lead. The reagents for the detection of lead,are water impregnated with sulphuret- ted hydrogen gas, and the hydrosulphuretsand hydro- guretted sulphurets of the alkalies and some of the earths, which throw down the lead in the state of a dark brown sulphuret, which may be reduced on charcoal before the blow pipe. Hahneman's wine test, which is made of sulphuret of lime and super- tartrate of potash in water, is nothing more than wa- ter impregnated with the hepatic gas. This test, o- riginally designed for the detection of lead in wines, is first mixed with a few drops of muriatic acid be- fore it is used, in order that, if iron be present, it will have no effect on that metal. Sulphate, muri- ate, and carbonate of soda have also been used as reagents; they form respectively, a sulphate, muri- ate, and carbonate of lead, precipitates which are (171 ) immediately blackened by hepatic gas. The sub- earbonate of ammonia, is preferred by many; it forms a carbonate of lead, which is blackened in the same manner, and is readily reduced on charcoal be- fore the blow pipe. Chromate of potash produces a yellow precipitate (chromate of lead,) with saturnine solutions. Salts of lead are also characterized by a white precipitate, with ferrocyanate of potash, and a yellow by the hy- driodate of potash. Infusion of galls produces a dingy yellow precipi- tate with solutions of lead: hence gallic acid has been recommended as a test for lead. The insolu- ble salts of lead, or those that are insoluble in water, as sulphate of lead, may be decomposed by soda or potash, and the oxyde of lead then dissolved in ni- tric acid, which may be examined by the reagents already mentioned. The metal may be obtained oy reduction. See Adulteration of Wine, Lecture I. PREPARATIONS OF BARYTES. The salts of barytes are generally poisonous.-— All die salts of barytes are white, and more or less transparent. The soluble sulphates produce with the muriate, nitrate, and other soluble salts of this earth, a precipitate of sulphate of barytes, which is remarkable for its insolubility in nitric or muriatic acid. If carbonate of barytes, which is also delete- rious, be swallowed by mistake, the proper antidote is Jil t d sulphuric acid; and the couuter-poison for the soluble salts, such as the muriate and nitrate of ( 172 ) barytes, is the speedy administration of a solution oi sulphate of soda. In both cases, an insoluble salt of barytes is produced. Orfila (Traite des Poisons, Tom. p. 167,) prefers sulphate of soda as an anti- dote. The native sulphate of barytes, heavy spar, or ba- roselenite, is found abundantly in every country, and a variety is met with in Derbyshire, called cawk.— The artificial sulphate is used as a pigment, under the name of permanent white. The Bolognian stone, from which the Bolognian phosphorous is formed by calcination, is the same sulphate. The native carbonate of barytes, called ivitheriie. barolite, aerated baroselenite, he. is about 4.3 specif- ic gravity, effervesces with acids if assisted by heat, and is only soluble in 4304 times its weight of cold water. Sulphate of barytes is the most insoluble substance which chemistry presents, requiring 43. 000 parts of water to dissolve it at 60 deg. The detection of barytes is readily performed.— If it be the sulphate it must be decomposed by car- bonate of potash m a crucible; then digest the mass in water; and decompose the carbonate of ba- rytes, thus formed, by nitric acid. The nitrate may be either exposed to heat to obtain the pure earth, or acted on by a solution of sulphate of soda, and the quantity of sulphate of barytes estimated. The car- bonate may be examined by solution in nitric acid, he. as before. Professor Brande (Manual of Chemistry, article ( "3 ) Strontium,) very judiciously observes, in speaking of the resemblance between strontian and barytes, which has led to confusion in analysis, that " they are both found native in the states of sulphate and carbonate only ; both sulphates are soluble in excess of sulphuric acid, and nearly insoluble in water; they are decomposable by similar means, as well the na- tive carbonate: they are both crystallizable from their hot aqueous solutions, and both attract carbonic acid. The carbonates are each soluble with effer- vescence in most of the acids; but the native car- bonates are not so easily acted on as the artificial.— Pure ammonia precipitates neither one nor the other. The following are essential distinctions: Barytes and all its salts, except the sulphate, are poisonous. The corresponding strontitic salts are innocent. Ba- rytes tinges flame yellow; strontian red. Strontian has less attraction for acids than barytes; hence the strontitic salts are decomposed by barytes. The greater number of the barytic salts are less sol- uble than those of strontian, and they differ in their respective forms and solubilities. Pure barytes is ten times more soluble in water than pure strontian." Furthermore, in your text book on Mineralogy by Professor Cleaveland, the distinctive, as well as the chemical characters ofthe sulphate and carbonate of barytes, and those of stroutaiu are accurately describ- ed, with the habitudes of each Ik; iv the blow pipe; to which I refer you, for further information on this subject. Carbonate of barytes has been recommended by 15* ( 174 ) Dr. Taylor, in lieu of arsenic, as ratsbane, and it, said to be preferable for the destruction of rats. He uses half an ounce in powder with four ounces of oat- meal, scented with six or eight drops of oil of ani6- seed. The same care, however, is necessary as in using white arsenic. It may not be irrelevant to observe, that in using those active poisons, the vessels, he. ought to be thrown away, and all descriptions of food safely secured from the depridations of the rats, for aftereating of the poison they go instinctively in search of water, food, he, PREPARATIONS OF ANTIMONY. Tartar emetic is a preparation of antimony, con- sisting of tartaric acid, oxyde of antimony and pot- ash ; and is, therefore, a triple salt denominated tar- tarised antimony, or tartrate of potash-and-antimony. It is nothing more than the supertartrate of potash saturated with the prot oxyde of antimony ; and as the excess of acid in that salt combines with, and is neutralised by, the oxyde of antimony, the emetic tartar may be considered a combination of the two salts; viz. tartrate of potash, and tartrate of antimo- ny. The action of reagents on this salt will detect its presence. Thus sulphuric, nitric, and muriatic acid decompose it, and precipitate a supertartrate of potash; soda, potash, and ammonia, preciptate an oxyde of antimony, and the carbonates of these alka- lies also affect it in like manner; the alkaline hydro- ( 175 ) sulphurets precipitate Kerme's mineral, well knowc by its colour; and when exposed to the action of a red heat, it first blackens and leaves a residuum of metallic antimony and subcarbonate of potash. The precipitate produced in the above experiments, when mixed with black flux, and exposed to heat will pro- duce a globule of metallic antimony. Tartar emet- ic, as its name expresses, when administered in cer- tain doses, excites vomiting; but when given in an under dose, is capable of acting as a poison. The best antidote in that case is sulphuretted hydrogen waters, which unites with the antimony and converts it into a mild sulphuret. Various demulcent drinks, infusion of bark, &c. may also be given. NITRATE OF SILVER. This salt is an active poison. It is a preparation of silver, in which the metal is dissolved by nitric acid. It is the lunar caustic of the apothecaries. It it known, that muriate of soda decomposes it, and forms a muriate of silver ; hence it is used as an an- tidote. A solution of muriate of soda swallowed im- mediately after taking the nitrate of silver, will form an insoluble muriate, and the stomach is then to be emptied by an emetic. MURIATE OF TIN. This preparation is also poisonous. If swallowed by accident, milk should be administered without delay. ( 176 ) It produces with it a coagulum of a mild and inof- fensive nature. CORROSIVE ACIDS. On the principle that alkalies combine with, an'5 neutralise acids, they are the most proper countt poisons to be administered in case of the accidental swallowing of corrosive acids. They must be used, however, in the form of solution, sufficiently diluted. Magnesia, or its carbonate, may also be administer- ed. Mr. Fourcroy advises, in case of sulphuric acid being swallowed, the speedy exhibition of a solution of soap, or a mixture of carbonate of lime, or car- bonate of magnesia. CAUSTIC ALKALIES. On the same principle that alkalies neutralise acids, and render them inert, the acids are used to counter- act the effect of alkalies when taken into the stom- ach. The acids preferred for this purpose, are ace- tic, or if it cannot be had, common vinegar, or lem- on juice. They will unite with the alkali and pro- duce either an acetate or a citrate, thus destroying the corrosiveness of the alkali. OXALIC ACID. This, acid is contained in the juice ofthe oxalis acetosella or wood sorrel, in combination with pot- ash, forming the salt known under the name of salt ( 177 ) •f sorrel.* It is formed artificially by the acidifica- tion of sugar, by means of nitric acid; hence it is al- so called saccharine acid. It has a powerfully acid taste, and precipitates lime from lime water almost Immediately, producing an insoluble oxalate of lime. Having the appearance of, it has been sold for, the sulphate of magnesia, or Epsom salt; a salt which it resembles in its crystallization. The mere taste, however, is sufficient to distinguish them; the oxa- lic acid is decidedly acid, while Epsom salt is deci- dedly bitter. Epsom salt is precipitated by carbon- ate of potash, but oxalic acid is not. Lime water has no effect on sulphate of magnesia; but with oxa- lic acid it forms an insoluble oxalate of lime. • Oxalic acid has been sold in London under the name of " Salts," and is usually bought for the pur- pose of whitening boot tops. Two or three drachms of it swallowed by mistake, will act as a violent poi- son. Very fatal accidents have already occurred by such mistakes. The immediate rejection from the stomach of this acid, by an emetic, together with copious draughts of warm water holding in solution bicarbonate of potash or soda, may be repeatedly given. Chalk and magnesia, diffused in water, may also be administered. In fact, a mixture of chalk * The oralis ace'osdla, oxalis corniculata,and different species of rumex, and the geranium acidum contain the oxalic acid in the state of binoxalate of potash. It is also found in the root of rheubarb ; the same salt, Scheele discovered in a variety of roots and barks, and Vauquelin and other chemists observed the. oxalic acid uncombined in the liquid which exudes from fhe cicerparieiiniim. ( 178 ) and water is recommended as the best antidote, be cause the oxalic acid by combining with the lime Oi the chalk, will produce an insoluble and inert com- pound, the oxalate of lime* ----------------- 137 * We lately saw in the Journal ofthe Royal Institution, a com- ment by the editors on the use of blue paper, which covers su- gar loaves, as a test for oxalic acid recommended by some per- son. It will only discover, like litmus, the presence of an acida without pointing out, or designating the kind. Its acid nature can, as readily, be determined by the taste. While noticing the, effect of acids or litmus, &,c. the following remarks may not be rrrevelant: Many vegetable substances may be employed as tests for un- combined acids and alkalies. Thus litmus is a test for acids, which redden it; and reddened litmus is also a test for alka- lies, which restore the original blue colour. This effect is ow- ing to the mutual saturation of each other ; for an acid and al- % kali, completely neutralized, neither indicate by reagents a/rec acid, nor a free alkali: if either one or other be in excess, the fact will be readily shown. Alkanet root is recommended, in Silliman's Journal, vol. v, p. 348, by professor Hare, as a substitute for litmus. When Used as such, he remarks, that it produces the same phenomina as litmus, but in a reversed order. The infusion or rather tinc- ture of alkanet, is made blue by an akali, and restored to its ori- ginal colour, red, by an acid. Paper stained with alkanet, ren- dered blue by alkali, is, therefore, a good test for acids, and vice versa. The sirup of violets becomes red by acids, and green by alkalies- and the same effect t;.kts place with the juice of March violets,, or that ofthe scrapings of raddishes. The blue Iris, according to professor Olmstead, (Silliman's Journal, v, 40.'.,) affords a good test for liquor. As tests for alkalies, reddened litmus, tincture ol brazil wood, tincture of turmeric, acidulous tincture of cabbage, and sirup of violets-are used. The first turns blue, the second mote of ( 179 ) HYDROCYANIC ACID. This acid, called also the prussic, is extremely virulent, producing death almost instantly, if the quantity taken be even very small. It has, howe- ver, been used in medicine, but in very small dos- eto It is this acid which exists in those cordials, made from bitter almotids, peach kernels, he.— Some of which have caused immediate death. The prussic acid has a strong smell of peach blos- soms, or bitter almonds; its taste is first sweetish, then acrid, hot, and virulent, and excites coughing. less so, the third reddish brown, the fourth blue, and the fifth green. These tests are generally very delicate. Thus, Bergmann has shown that papei stained with litmus, is reddened, when dipped into water containing 1.3021 of sulphuric acid ; and the infusion of turmeric will become brown when the soda, in the water, amounts only to 1.2217th part. Paper stained with Bra- zil wood, Bergmann ascertained would become blue in water containing only 1.9915th part of carbonate of soda in solution. These effects clearly prove, that chemical action is exerted in infinitely small ratios. On the delicacy of tests we may add, that Dr. T. Thomson has detected in water the one millionth part of its weight of lead by sulphate of soda. Nitrate of silver will detect muriatic acid in minutely small proportions ; for one grain of common salt, dissolved in 42.250th grains of water, (rather more than 5 lbs.) will give a precipitate. This quantity does not contain more than 1.108333 part of its weight of muriatic acid. Other instances may be mentioned of the power of reagents; as starch, which will indicate iodine in solution, in the infinitely small proportion of 1.450000, and tannin, which will form an immediate precipitate in a solution of 1.1000 of isinglass, and a very considerable precipitate when the gelatin is only 1.2000. ( 180 ) The water obtained by the distillation ofthe leaves of the lauro-cerasus, (of which notice has already been taken,) bitter kernels of fruits, and some other vegetable substances, are poisonous, on account of their containing this acid. Mr. Schrader, of Berlin, ascertained the fact that the water obtained from these substances, when mixed with lime-water gave a blue precipitate with sulphate of iron. In this ex- periment, the lime by uniting wdth the prussic acid, forms a hydrocyanate of lime, which, with the sulphate of iron, is decomposed; and produces a precipitate of the per ferrocyanate of iron, the hydrocyanic acid be- ing changed by a portion of the iron into the ferro- cyanic. The addition of lime water, or a very weak solution of potash, to distilled waters supposed to contain prussic acid, and the subsequent addition of sulphate of iron, will indicate its presence. Free prussic acid gives with nitrate of mercury, a black precipitate. Scheele found that prussic acid gave a white precipitate with nitrate of silver, and with ni- trate of mercury, a black. We have the following instances of the effects of the prussic, or hydrocyanic acid: In the Annates de Chimie for 1819, we are inform- ed, that M. B. professor of chemistry, left by acci- dent on a table, a flask containing alcohol impregna- ted with prussic acid; the servant enticed by the the agreeable flavour of it, drank a small glass of it. In two minutes she dropped down dead, as if struck with apoplexy. Orfila remarks, that Scharinger, a professor at Vi- enna, prepared some concentrated prussic acid; he , < 1*1 ) spread a certain quantity on his arm, and died a lit- tle time thereafter. From the experiments of Mr. Mogrndie it ap- pears, that pure hydrocyanic acid is the most viru- lent of all poisons. A rod dipped into it, and brought into contact with the tongue of an animal, will occa- sion death before the rod can be withdrawn. A bird held over the mouth ofa phial containing the acid. is almost instantly killed. The following melancholy accident, which has lately occurred, is no doubt to be attributed to the hydrocyanic acid : "The Edenton (N. C.) Gazete states, that a small child, about 2 yeurs of age, after eating a number of yellow jessamine flowers, died in the space of half an hour. In a minute or two after eating them, she became perfectly blind." Eaton (.Manual of Botany, p. 321,) describes two species of jassamine, or jasmine, the fruticans and officinale. The latter afford white flowers, and ex- hale a sweet and penetrating odour, particularly af- ter rain. It is the common jasmine. The Italians prepare from the flowers, by means of cotton soak- ed in oil, a grateful perfume. See Essential oil. There can be no question as to the poisonous pro- perties ofthe yellow jessamine, from the instance above mentioned. If distilled, the water, we are of opinion, would give every indication of prussic acid. 16 ( 182 ) POISONOUS VEGETABLES. Professor Eaton in his Manual of Botany, and in his Botanical Dictionary, has given a few concise rules- for avoiding vegetable poisons, which we here in- troduce. PLANTS NOT POISONOUS. 1. Plants with a glume calyx, never poisonous; as wheat, Indian corn, foxtail grass, sedge grass, oats. Linnaeus. 2. Plants whose stamens itand on the calyx, never poisonous; as currant, apple, peach, strawberry, thorn. Smith. 3. Plants with papilionaceous flowers, rarely if r^ver poisonous; such as the pea, bean, locust tree, vild indigo, clover. Smith. 5. Plants with labiate corols, bearing seeds with- out pericarps, never poisonous ; as catmint, hysop, mint, motherwort, marjoram. Smith. 6. Plants with compound flowers, rarely poison- ous : a3 sunflower, dandelion, lettuce, ^ burdock.— Milne. POISONOUS PLANTS. 1. Plants with five stamens and one pistil, with a ^lull-coloured lurid-corol', and of a nauseous sickly smell, always poisonous; as tobacco, thorn apple, henbane, nightshade. The degree of poison is di- minished where the flower is brighter coloured, and ( AS3 j the smell is less nauseous. As potatoes are less poi- sonous, though ofthe same genus with nightshade.— Smith, p. 415. 2. Umbelliferous plants of the aquatic kind and of a nauseous scent, are always poisonous; as water-hem- lock, cow-parsley. But if the smell is pleasant, and they grow in dry land, they are not poisonous; as fennel, dill, coriander, sweet cicely. Smith, p. 416. .3. Plants with labiate corols, and seeds in cap sules, frequently poisonous; as snap dragon, fox- glove. 4. Plants from which issue & milky juice on being broken, are poisonous, unless they bear compound flowers; as milkweed, dogbane. Milne. 5. Plants having any appendage to the calyx or corol, and eight or more stamens, generally poisory mis; as columbine, nasturtion. Linnacu*. MOST OENEIUR RUM!. Plants with few stamens, not frequently poison- ous, except the number be five: but if the number be 12 or more, and the smell nauseous, heavy, and sickly, the plants are generally poisonous. In reference to the eualkA- of plants, it is observ- ed, that plants of the same taste and odour, are ge- nerally possessed of similar qualities, and that the smell and iwsi.e are always the same. Richard di- vides the odours into fragrant, aromatic, ambrosial, (resembling amber,) alliaceous, foeted, and nauseous. On this division, Mr. Eaton observes ; "As the fra- { 184 ) grant, the aromatic and ambrosaic, are always free from all hurtful qualities, and as the fceted and nau- seous, are generally poisonous, it seems that man- kind have in some manner an instinctive principle by whicli food is to be selected." In the preparation of secret poisons, of which we have already spoken, sundry poisonous vegetables, as the aconitum, were used; and it was the custom with the ancients to put criminals to death by the ad- ministration of potions consisting of nightshade, aquatic hemlock, aconitum, and other similar poi- sons. Thus the Athenians sacrificed one of the best and greatest of men, Socrates, by a cup of poison, said to have been made of hemlock !* In concluding these remarks, it may be useful to add, that no plant is more injurions in its effects on the human frame than the deadly nightshade, or atro- *History informs us, that Solon, the celebrated Lawgiver, used a strategem against the Cirrhaeans, by "poisoning" their water. He changed the course ofthe river Plistus, which run through the town, and which it seems served them with water. The inhabitants, however, held out during that time against the besiegers. " He caused roots of Hellebore to be thrown into the Plistus, and when he found it was fully poisoned, turned the river in its proper channel: the Cirrhaeans drinking greedily of that water, were taken with a continual flux, and forced thereby to give over the defence of their works." Hist. Phil. art. So- lon. The root ofthe Hclleborus hyemalis has been examined by Vauquelin, with the view of ascertaining the nature ofthe bit- ter and acrid principle it contains. The principle he found to be an oil of a peculiar nature, which is extremely poisonous, and, according to Vauquelin, is to be found in many plants, and is the cause of their poisonous qualities ( 185 ) pabelladona; and the alluring appearance, and sweet- ish taste of the berries have in many instances, par- ticularly with children, been succeeded by the most fatal consequences. Several cases are mentioned of persons having swallowed three or four of them, and even -x single berry or half a one, and produced death. The leaves are more powerful than the ber- ries. They have, however, been used in medicine. both externally and internally, but with great cau- tion. The atropa beiladona, which is poisonous in all its parts, produced, when eaten, what the ancients call- ed strychnomania. Plutarch describes certain strange and dreadful effects of a vegetable poison on the Roman soldiers, under the command of Anthony, during their retreat from the Parthians. This vegetable poison, it is supposed, was the deadly nightshade. "Their dis- tress for provisions," says Plutarch, " was so great, that they were compelled to eat of the plants un- known to them. Among others they found an herb, of which many of them ate; who shortly afterwards lost their memory and their senses, and wholly em- ployed themselves in turning about all the stones they could find; these were then seized with vomiting and fell down dead !" The stramonium, thorn apple, or James-Town weed, (datua stramonium,) a weed common in the United States, of which it is a native, and is abund- ant on the Point, when taken internally, will occa- sion giddiness, torpor, and sometimes even deata,=~ 1*6* ( 186 ) Notwithstanding, it is an article in the Materia Med- ica, and has been used successfully in cases of epilep- sy and convulsive disorders; and externally, in the form of ointment, for inflammations. The soporif- erous and intoxicating qualities of stramonium are well known in the east, where it has been very im- properly employed. The seeds are particularly in- jurious. Persons should be careful not to swallow them, as very alarming symptoms have been observed in such cases. The nut of the Haocevay, a tree which grows in Brazil, is said to be a violent poison. Opium possesses certain poisonous and narcotic properties, which are attributed to a substance call- ed morphia. Morphia is a peculiar principle obtained from opi- um, which, in consequence of being capable of neu- tralising acids, is considered a salifiable base. This substance was called the narcotic principle, as it was found to possess the intoxicating and poisonous qual- ities of opium. Dr. Thomson remarks, that when it is swallowed it produces the same effects as opium itself; but it .acts much more powerfully when in a state of solution; and when in the solid state, it scarcely produces any effect, owing to the little ac- tion of the juices of the stomach on it. Orfila, (Ann. Chim. et de Phys. v. 288,) assures us, that its poi- sonous effects are counteracted by the vegetable acids, particularly vinegar, which are supposed to neutralise it. There is an acid which exists in opi- ( !«' ) am, called the meconic acid; it is supposed to be united with morphia. We are but little acquainted with the principle, or principles, of vegetable poisons. But it may appear remarkable, that the same elementary substances, should constitute in one instance a harmless sub- stance, and in another, a most virulentpoison. Thus, the dry poison of the viper, a poison in its fluid state which occasions the fata1 effects ofthe viper's bite, when submitted to experiment, exhibits all the char- acters of gum arabic, in its appearance, in its feel, in its solubility in water and insolubility in alcohol, in its precipitation from water by alcohol, and in many other characteristic properties of that gum ; and'yet, notwithstanding these facts, and the experiments of Fontanaon the dry poison ofthe viper, and on gum arabic, from which he obtained the same results, how different are the effects of the two substances ! A humiliating proof of the insufficiency of chemical analysis, and of our little acquaintance with the spe- cific principles of animal, and some vegetable poi- sons. The leaves of the deadly nightshade have been examined by Melandri and Vauquelin. The latter obtained from them vegetable albumen, or gluten, a bitter nauseous substance, which constitutes the nar- cotic part ofthe plant, and nitrate, muriate,sulphate, mperoxalate, and acetate of potash. ( 188 j yERIAL POISONS. Several gaseous substances are known to destroy life ; for the only proper air for the maintenance of life is that ofthe atmosphere, composed of a due pro- portion of oxygen and azotic gases.* It is unne- cessary to name the deleterious gases, as it is known * According to Mr. Cavendish, atmospheric air is composed of 10 parts by bulk, of oxygen, and 38 parts ot azote, or 7«.16 azote, and 20.82 oxygen in the hundred. All the different ex- periments, which have been made at different times with eudi- ometers of various constructions, agree in their reult, that the proportion ofthe component parts of air are always the same; viz. about 0.21 parts of oxygen gas, and 0.79 of azotic gas.— Atmospheric air always contains water, even during the dryest time. The hydrometer is an instrument employed to determine the degree of moisture. The state in which water exists in the air is either by solution, in the same manner as water dissolves salt, or by meenanical suspension or mixture ; the first is what is understood by vapour, and the second by steam. The quantity of vapour varies in the atmosphere, from 1.60th to 1.300th part ofthe atmosphere. Dalton judges that the medi- um quantity amounts to about 1.70th of its bulk. Carbonic acid gas exists also in the atmosphere, even at the greatest heights. Saussure found it at the top of Mount Blanc, the highest point of the European continent. By Dalton's experiments, the bulk of carbonic acid does not much exceed 1.1000 of the atmos- phere. But immense quantities of carbonic acid must be con- tinually forming, and mixing with the atmosphere, as it is known that respiration, combustion, and several other process- es will produce it, which are going on continually. Other bo- dies are contained in the atmosphere, and are frequently detect- ed in certain situations; thus hydrogen gas, carburetted hydro- den gas, which is oftea emitted by marshes, contagious mat- ter, &e. f 189 ) that all of the gases, with the exception of oxygen and the protoxyde of azote, cannot be inhaled with- out eminent danger. The most common gas of this description is one, which is very familiar to you, namely, carbonic acid, or fixed air. This gas is ge- nerated by combustion, especially of coal, and by the vinous fermentation and several other processes ; and is found abundantly in mines, where it is called choke damp, and in caverns, wells and cellars. It is usually recognized by letting down a burning taper into the well or cellar; which, if it be present in a- ny quantity detrimental to animal life, will be imme- diately extinguished. A portion collected in a bot- tle, and shook over lime water, will render the water turbid, forming carbonate of lime, which will be dis- solved by an acid with effervescence. Thus, by the property which carbonic acid has of extinguish- ing flame, and by its precipitation of lime from lime wetter, the presence of the gas is readily detected. As a corrective, either fresh air should be admitted in the well or cellar by means of wind-sails, or quick- lime thrown in ; in the latter case, it will be absorb- ed, and combine with the lime. Nothing is more fatal than sleeping in close rooms, with a charcoal fire, especially if there be no means of ventilation. Many instances are recorded of death having occurred by this deleterious air. Per- sons who fiave been suffocated, or animation sus- pended by breathing this gas, should be taken into the open air, and treated in the same manner as in ether instances of apparent death. V ( 190 ) The gaseous oxyde of carbon, according to Mr. Nicoll, has occasioned a singular disease among the workmen of a cotton manufactory at Argues, near Dieppe; and those who worked in the upper stories of the mill were particularly affected. A short ac- count of the disease is noticed in Silliman's Journal, vol. vi. p. 199. It seems that the carbonous oxyde gas resulted from the decomposition of the oil by the heat of a cast iron stove, on which they were in the habit of placing their vessels of that fluid. The gas being lighter than atmospheric air, made its way to the upper stories of the manufactory, where it produced the most dangerous effects, such as vertigo, convul- sions, a disordered imagination, he. This, I be- Jieve, is the first instance on record of the deleterious effects of this compound of carbon and oxygen. By the experiments of Mr. Davy, carbonic acid produces an acid taste in the mouth and fauces, and a sense of burning at the top ofthe uvula : and v\hen arrived at the upper part ofthe trachea, it is instant- ly stimulated to such a degree as to excite a spas- madic contraction of the glottis, and renders it in- capable of transmitting a particle of air into the lungs. The same effects are produced even when diluted with an equal bulk of atmospheric air. But when the proportion of the two gases is about three quarts of carbonic acid to nine of atmospheric air, the mixture may be breathed for a short time with impunity. This gas has been recommended in the cure ef diseases of increased excitement, as pulmo- nary consumption. Patients of this description ( 191 ) have been persuaded to visit daily brew-houses, where there is constantly a copious production of fixed air. The quantity of carbonic acid gas in atmospheric air may be learnt by eudiometry. If 100 parts of atmospheric air be thrown up a graduated tube, cal- led an eudiometer, standing over lime water, the carbonic acid will be absorbed, and the amount of absorption will be shown by the scale. If the same quantity of atmospheric air be exposed to liquid sulphuret of potash, or in preference Davy's solution of nitrous gas in green sulphate of iron, the oxygen will be absorbed, and its quantity ascertained. The air which remains is azote. The quantity of hydro- gen gas is usually determined by Volta'seudiometer; by detonating a given quantity of air, supposed to con- tain it, with a due proportion of oxygen gas, he. There are certain noxious effluvia of a gaseous na- ture, termed miasmata, which by mixing with atmos- pheric air, communicates to it a poisonous quality: the breathing of, or coming in contact with which, con- stitutes disease very often of a malignant nature. What this miasmata is composed of in all instances, is very uncertain. Thus the miasmata of marshes, of low wet morassy ground, &tc must be produced as well by vegetable as animal putrefaction, and con- sist of carburetted and sulphuretted hydrogen gas. some ofthe compounds of azote, he. carrying with them perhaps ?ome specific poison, which produces intermittent, remittent, and other fevers. But the miasmata, we know, from its effect on the system ( 192 ) differs considerably in its nature ; and its virulence is in proportion as it is concentrated or diluted with atmospheric air. If in Cuba, or any of the West In- dia Islands, in New-Orleans, or other cities to the south, where the heat in summer is intense, a certain miasmata should be produced by the concurrent cor- ruption of animal and vegetable matter, which produ- ces the yellow fever ; are we not to believe that the same cause would produce the same miasmata in New-York, Philadelphia, or Baltimore, and occasion a disease ofthe same type, and equally malignant? Inasmuch as causes operating in all respects alike, and similarly circumstanced, must produce the same ef- fects ; it is but reasonable to conclude, that in order to prevent a recurrence of the yellow fever, the cau- ses which produce the serial poison alluded to ought to be removed, i. e. all putrifying animal and vegeta- ble matter, from streets, alleys, and by-places; and, where they have been, the frequent use of fumiga- tions. Whether the mismata be cyanogen, or car- buret of azote, or any of its compounds, or any other gaseous substance, we will not inquire.* It is a * See an essay of the author, "On the formation of cyanogen or prussine, in some chemical processes not heretofore noticed,'' in the American Journal of Science and Arts, vol. vi,p. 149. There is a poisonous wind in the desert of Arabia, called sa- miel, which kills without any apparent change on the body, ex- cept a total privation of irritability, and sometimes a distension ofthe blood vessels, an i extravasation of their contents. The samiel, called also the simoon, comes from the northwest quar- ter. It is said to be. a blast of hydrogen gas; but this is alto- gether conjecture. ( 193 ) sufficient to attend to the fact, and apply a remedy for the evil. The ancient Grecian story ofthe hydra, or many headed monster, which inhabited the marsh or fen of some extent, called Lerna, in the Peloponesus, be- tween Mycente and Argos, had its origin in the pes- tilental miasmata, whick extended its influence to a considerable distance. The hydra was considered by Virgil as a fictitious, or poetical animal; and al- though Bochart endeavored to make the whole story literally intelligible, as that Hercules was sent by Eurystheus to fight this formidable creature, and a crab came forth to his assistance, which was crush- ed by Hercules ; yet Lancisi, physician to Pope Clement XI. with a clear and discriminating mind, perceived that important physical truths were con- cealed under this allegory. In a letter from the lear- ned Dr. Mitchell, to the late Dr. Priestley, in 1799, the Lernian hydra is accounted for by the doctor, in which he explains very satisfactorily what was meant by the hydra. " The word hydra," says the doctor, " is derived from a Greek word, signifying water. This fluid then, detained upon the marsh of Lerna, favoured occasionally the production of unwholesome exhala- tions. Such vapours being at once injurious and in- visible, were ascribed to some preternatural enemy or destructive monster; and being diffused or wafted around the country, and often cutting off b«th men and beasts, were fancied to be the effect of the sup- posed monster's poison. According to her extent 17 I 194 ) and virulence, was she reported to have fewer or more heads for preparing and inflicting this poison." The doctor gives many ingenious opinions respect- ing the drawing off the water, leaving the mud and slime, which he interprets the " cutting off a head ;" the increase of deleterious gases, by exposing such a naked surface, or the sprouting forth of two in its place; the cauterising effect of the solar heat: the crab, or hydra's ally, as showing the frequent re- currence of difficulties to overcome them ; the allego- ry of Hercules, meaning the insuperable courage and difficulties in the attempt, to which he adds the cher- sydra, who remained after the marsh or fen had dri- ed up, derived from two n which exists in tobacco. Vegetable substances are frequently deleterious in their natural state. We have a prominent instance of this in the cassava or cassada of the West Indies. In its crude or unprepared state it acts as a most dead- ly poison ; but when the juice is expressed, and the root afterwards baked, it becomes a wholesome and nutritive food. Emetics of sulphate of zinc, and tartar emetic, are used in the case of vegetable, as with mineral poisons; after which the patient should be made to drink copiously, if possible, of liquors acidulated with the juice of lemons, vinegar, or sulphuric acid, giv- ing the preference, however, to the former. A powerful antidote against vegetable poisons has been recommended by M. Drapier; it is the fruit of the feuUlea cordifolia. He gave dogs the rhus toxi- codendron, hemlock, and nux vomica^ and all those that were left to the effects of the poison died, but those to which the above fruit was administered re- covered completely, after a short illness. To ascer- tain whether the antidote would act externally, he «eok two arrows, which had been dipped into the ( 200 ) juice of the manchenille, and slightly wounded with them two cats. • To one of these wounds he applied a poultice of the fruit, while the other was left with- out any application. The former produced no in- convenience; but the wound ofthe other, containing also the poison, caused convulsions in the animal, and death ensued. The Scutellaria lateriflora, recommended by the late Dr. Spaulding, is said to be an infallible means for the prevention and cure of the hydrophobia after the bite of rabid animals. We may add here, that the pure water of ammonia (aqua ammonia pur Vauquelin on human hair. With common hair, a weak solution of potash will dissolve it, so will the acids very gradually, and alcohol will extract from it two kinds of oil. The colouring matter he supposes is an oil, which is blackish green in black hair, and white in white hair. Nothing, however, is particularly known as to the composition of different kinds of hair. WTe may add, that Vauquelin detected an animal matter, a solid oil, a greyish green oil, iron, oxyde of manga- nese, phosphate of lime, carbonate of lime, silica. and sulphur. We will now consider another branch of our enqui- ry, namely, the detection of sundry adulterations in chemical preparations, fyc. used in medicine and the arts. The adulteration of articles is carried to a great extent in Great Britain; and if we believe Mr ( 207 ) Accum, it would seem, that nine tenths ofthe most potent drugs and chemical preparations used in Phar- macy, in London, are vended in a sophisticated state by the dealers who would be the last to be suspect- ed. The same may be said of sundry pigments 01 colouring substances; of acids; alkalies; materials used in the arts; soaps ; dye-stuffs, and a long cate- logue unnecessary to enumerate. The practice of sophisticating articles has been common with all nations. Professor Beckman, in speaking ofthe manufacture of colours, hints at these adulterations. " Thus,"says he," they (the Dutch,) pound cinnaber and smalt finer than other nations, and yet sell both these articles cheaper. In like manner they sift cochineal, and sell it at a less price than what is unsifted." In London, we are assured by Mr. Accum, that nine tenths of the drugs and pre- parations are adulterated, which pass through the hands of dealers. The same may be said with ma- ny of our retail, and well as wholesale dealers; for the fact is too well known to be refuted, that a num- ber of articles are frequently mixed, and otherwise intentionally adulterated. Is there any instance, I would ask, of a more palpable fraud than that of manufacturing out of one seroon of merchantable in- digo as many as five or six, or more, and imposing it on the public as genuine indigo? A fi'aud which was practised some years ago in Philadelphia. Sup- pose a druggist were guilty of dyeing yellow bark red, or mixing with the powdered bark a quantity of bol armen. and selling it as the genuine red bark; ( 208 ) or of grinding with the crystals of tartar sulphate of potash, &e. in order to increase the quantity of cream of tartar; or mixing flour, he. with a variety of offici- nal roots in the powdering of them, or of performing any other adulterations, whether with drugs or co- lours, such deceptions would necessarily call for a mi- nute examination in all articles vended under so questionable a shape ? ULTRAMARINE. This pigment is made from the azure stone, or la- pis lazuli; and is a beautiful and unchangeable blue. The composition of azure stone is silica, alumina, sulphur, and soda. (M. M. Clement and Desormes Ann. de Chim. torn. 57.) The finest specimens are brought from China and Persia. The blue is manufactured from the azure stone as follows: The stone is made red hot, and plunged into water to render iteasily pulverisable. It is then powdered, and mixed with a varnish composed of rosin, wax, and boiled linseed oil, and the mix- ture is put into a linen cloth, and repeatedly knead- ed with hot water. The first water is thrown away ; the second gives a blue of the first quality; and the third, one next in value. This process is mechanic- al; for the colouring matter of the azure stone ap- pears to adhere less firmly to the foreign matter, with which it is associated, than it does to the resin- ous cement; hence its separation, and finally, by re- peated washings, he. with hot water, is deposit- ^ 209 ) red. Clement and Desormes, however, consider tht process as a species of saponification. A substitute has lately been recommended for ul- tramarine. It consists in mixing the phosphate of cobalt, which is an insoluble purple powder, (formed by decomposing the nitrate or muriate of cobalt with phosphate of soda,) with eight parts of gelatin- ous alumina, and exposing the mixture to heat. When Sir H. Davy examined the ancient pig- ments at Rome, an account of which he published in the Philosophical Transactions for 1805, he examin- ed also the Egyptian azure, a paint which had re- tained its colour for seventeen hundred years. He found that 20 parts by weight of opaque flints, 15 .parts of carbonate of soda, and 3 of copper filings, when exposed to the action of a strong heat for two hours, produced a substance of exactly the same de- gree of fusibility, which, in a pulverised state, gave a fine deep sky blue. The adulterated ultramarine, as it is usually mixed with indigo, Prussian blue, or some similar substance on account of their comparative cheapness, when mixed with concentrated nitric acid will undergo no immediate change; but the genuine ultramarine should become deprived of its colour. This is the most conclusive property. INDIGO. This is a blue colouring matter extracted from tht indigo plant,* and is nothing more than colouredfe- * Jadigo may be procured from the woad,^i«'(rfia tinctorial .18* ( 210 ) cula. When first extracted it is green, but becomes blue by exposure to air. Indigo should become green or greenish yellow when deoxydized, a process well known in dyeing. There are several qualities of indigo. It should contain, in general, 50 per cent. of pure colouring matter, which is insoluble in wa- ter. When exposed to a heat above 400 deg. F. it produces a crimson smoke, which is supposed to be the pure indigo, and when condensed it yields crys- talline needles. If any considerable residue remain, it indicates an adulteration, and with earthy or metal- lic substances, which may be analyzed. It should be- come green, or geenish yellow with 2 parts of sul- phate of iron, and one of lime; and in this green state be soluble in the caustic alkalies. It should also be soluble in sulphuric acid, forming the liquid blue dye, leaving little or no residue ; and when a little of this sulphate of indigo is diluted, the addition of iron or zinc should destroy its colour, which should also take place with chlorine. Hence a solution of indigo in sulphuric acid, has been recommended for measur- ing the strength of chlorine or oxymuriatic solutions in bleaching. Water when boiled on it should dissolve no more than about a ninth of its weight, leaving the colour- ing matter untouched. Indigo is insoluble in al- by digesting it in alcohol, and evaporating the solution. The crystalline grains, thus obtained, gradually become blue by the absorption of oxygen. But theindigo of commerce is procured from the wild indigo, (indigqfera argenta,) the Guatimala indi- go, (indigqfera disperma,) which yields the greatest quantity of indigo. It is prepared by fermenting the leaves of those t ees or plants in water. < 211 ; cohol; ether, and in fixed and volatile oils.— Muriatic acid has no action on the colouring mat- ter ; but when digested on it, it dissolves some earthy and extractive matter w th a portion of iron. Nitric acid, on indigo, converts it into artificial tan- nin, and it loses its colour. Pure indigo, when mix- ed with liquid fermentable materials, should be speed- ily deoxydized, and again become blue by exposure to the air. This is also a method of setting an indi- go vat. Indigo has been largely adulterated, and sold in our market. The adulteration, of which we speak, as it came to our knowledge, was effected chiefly with logwood and starch ; this compound was then mix- ed with a certain part of genuine indigo. This fraud, however, may be discovered by using the tests above mentioned, which will point out the adulteration either by showing the decided impurity of the indigo, or the quantity of foreign matter with which it is minced. By the method of adulteration, practised by a druggist then living in Philadelphia, who was detect- ed of the fact, one seroon of merchantable indigo would make of the spurious six or eight! The co- louring matter of the logwood was first imparted to the starch, a small portion of copperas being used, and the coloured starch was then mixed with a given quantity of the real indigo. The fraud, however, was soon discovered, but not until he had disposed of several seroons. Those acquainted with the quality of indigo, can form a near estimate of its kind, and t 212 ) purity. The break, or fracture of indigo is a good criterion. Sulphuric acid, we remarked, will dis- solve the colouring matter; if the residue should exceed a certain amount, it may be considered as foreign matter. Chlorine water is also.agood test. It is supposed that the indicon of Dioscorides, and the indicum of Pliny and Vitruvius, were the same as our modern indigo. It was a blue pigment brought from India, which, when diffused in water, produc- ed an agreeable mixture of blue and purple. It was often adulterated by tb,e addition of earth. On that account, the kind which was soft without any rough- ness, and which resembled an inspissated juice, was esteemed the best. Pliny (lib. xxxv. cap. 6, sec. "27, p. 688,) speaks of a method of distinguishing pure from adulterated indigo, which consists in burning it; the pure, he observes, gives an exceedingly beau- tiful purple flame, a fact already noticed, accompan- ied with a smell similar to that of sea water.— The ancients remarked, that good indigo when pul- verised is of a blackish colour. Mr. Beckman ob- serves, that in Pliny's time, people coloured a white earth with indigo in the same manner as coarse lakes. This earth was the annularia* or in Pliny's words, •" the beautiful white with which the ladies painted *>r ornamented themselves." The laccos chromati- noos, also of the ancients, is supposed to be our in- digo. During the reign of Queen Elizabeth, the import- ation of indigo was prohibited in England, and the prohibition was not taken off till the reign of Charles ( 213 ) u. It was also prohibited in Saxony, and Colbert restricted the French dyers to a certain quantity of it. It was considered a corrosive substance, and sailed food for the devil. ANTWERP BLUE. This paint or colour is frequently adulterated, and .sometimes with indigo. Ibis admixture may be detected by the use of chlorine ; for genuine Ant- werp blue will not be deprived of its colour when thrown into liquid chlorine. Chlorine has the pro- perty of discharging certain colours, but on this col- ouring substance it has no action. PRUSSIAN BLUE. This pigment is sometimes adulterated. When pure it should consist of nothing more than ferrocy- anic acid and per oxyde of iron. But in conse- quence of using allum in the process, in order to in- crease the quantity of the precipitate, the Prussian blue of commerce always contains alumina. The preparation of Prussian blue consists in cal- cining animal substances, particularly dried blood, according to the original recipe published by Wood- ward in 1724, with potash, dissolving the caleined matter in water, and adding the fluid to a mixed so- lution consisting of sulphate of iron and allum. The powder which precipitates is at first green, which is separated by filtiation, and muriatic acid is affusecl ( 214 ) upon it; it then assumes a beautiful blue colour. It is afterwards washed and dried. The perferrocyanate of iron when exposed to a heat of 400 deg. in the open air takes fire. When pure, neither water nor alcohol has any action on it. It is decomposed by boiling solutions of potash, so- da, lime, barytes and strontites, forming soluble fer- roprussiates, leaving a brown deut oxyde of iron, and a yellowish brown subferroprussiate of iron.— There are three characters, however, of the genuine Prussian blue, viz: adding aqueous chlorine, which will change the blue to a green colour, in a few mi- nutes, especially it the blue be recently precipitated; water impregnated with sulphuretted hydrogen gas, will change the blue to the white ferrocyanate of iron; and sulphuric acid, not diluted, will decom- pose and destroy its colour, which would not be the case altogether if it contained the least quantity of indigo, a substance with which it is sometimes adul- terated. The purple flame will also recognize the presence of indigo. It is used for the purpose of a paint, and alumi- na gives a body to the colour. VERDITER. This blue pigment is a preparation of copper, ob- tained by adding chalk to a solution of copper in ni- tric acid. It is, therefore a carbonate of copper.— All verditer, however, contains about 7 per cent of lime ; more than this quantity renders it of an infe- ( 215 ) nor blue. Sometimes, in fact, chalk is added, in or- der to adulterate it. It snould contain 50 per cent of pure copper. This may be learnt by dissolving a given quantity in nitric acid, and precipitating the metal by a piece of iron. The quantity of lime may be ascertained by adding to a portion of the nitric so- lution oxalate of ammonia, which will throw down an oxalate of lime. SMALT. This pigment is made by fusing glass with zaffre, in impure oxyde of cobalt, and pulverising the glass. The azure blue is prepared in the same manner. If adulterated, the fact may be known by the affusion of acids, he. as pure smalt or pure azure blue Wi.l not be acted upon by acids, except, however, the fluoric. It is observed, that the colouring matter of oxyde of cobalt on verifiable mixtures, is superior to that of any other metal. One grain gives a full blue to 140 grains of glass. Blue glass is coloured with oxyde of cobalt. A flux, as it is termed, of silica, potash, and lead, is coloured by the addition ofa small quantity ofyhe cobalt. Oxyde of cobalt is also em- ployed, for the same purpose, to give a blue glaze to pottery. Thus, likewise, in the imitation of some precious stones, it communicates a particular col- our. The beryl, for instance, is very accurately im- itated by fusing with a particular flux, called a paste, i mixture of glass of aatimony and oxyde of cobalt. ( 216 ) in the proportion of two of the latter to twenty-four of the former. Brice is levigated smalt, and rather lighter than the preceding. It may be examined as tb,e former. CARMINE. Carmine is a red pigment prepared from cochineal. It contains the colouring matter of cochineal, an in- sect which feeds on, and is supposed to derive its colour from the cactus opuntia. The colouring mat- ter of this insect, M. M. Pelletier and Caventou have named carminium, but Dr. John calls cochinelin. The properties of the colouring principle of cochi- neal are that it is fusible at 122 deg. very soluble in water, less so in alcohol, and insoluble in ether un- less by the intermediation of fat. Acids change it from crimson to a bright red, and then to yellow; alkalies, and protoxydes generally speaking, turn it to violet. Alumina combines with it, and forms a beau- tiful lake, or carmine. In the opinion of M. M. Pel- letier and Caventou true carmine is a triple com- pound of an animal matter, carminium, and an acid which enlivens the colour. Muriatic acid will change the colouring matter into a fine scarlet. Scarlet is produced exclusively with the colouring principle of cochineal, which is fixed upon wool by nitromuriate of tin and tartar. A crimson colour is produced by allum. Several processes are recommended for the pre- paration of carmine; some advise the use of solu- tions of tin and tartar, and others the use of allum, ( 9.7 ) •i of alumina. Carmine, heretofore, was supposed to consist ofthe colouring matter of cochineal, uni- ted with oxyde of tin, or with alumina. It is an ex- cellent, but very expensive colour, and is liable to adulteration. Mr. Accum assures us, thatgenuine carmine should lie entirely soluble in liquid ammonia. Should car- mine contain vermillion, the fact may be known by examining it in the same manner as Florentine lake. Carminium, or the colouring matter of cochineal, is very soluble in water; and the watery solution has a fine carmine colour. Without noticing the action of different substances, it will be sufficient to remark, that chlorine acts on this colouring matter very con- siderably, giving it first a yellow colour, which, it gradually destroys altogether. If no animal substance be present, it occasions no precipitate in the solution of carminium in water; and hence chlorine water is recommended, as a reagent, to discover the presence of animal matter in this colouring principle. Iodine has the same effect as chlorine, but in a less sensible degree. FLORENTINE LAKE. This colour is prepared from the refuse cochineal liquor, left after the separation of carmine, with a small addition of Brazil wood, and precipitating by allum, or a solution of tin. Sometimes Brazil wood is altogether used. In that case the pigment is very inferior. Florentine lake should contain neither vermillion 19 ( 218 ) uer red lead, nor indeed any foreign pigment. If a Small portion be exposed to the action of the blow pipe on charcoal, the lead will be discovered by a metallic globule; or by dissolving the lake in nitric acid, and adding hydrosulphuret of ammonia, or an\ ofthe tests for lead. Vermillion will be volatilized by heat. If a small portion ofthe suspected lake be mixed with a little lime, and exposed to heat in a glass tube, the vermillion, if it be present, will be decomposed, and mercurial vapour be condens- ed in minute globules on the sides of the glass. MADDER LAKE. This is the colouring matter of madder, (rubia lintogpm,) obtained by adding to an infusion or a decoction of that root, first a solution of allum, and afterwards another of potash. It is, of course, likt similar lakes prepared with allum, a combination oi colouring matter, and alumina. The examination of this lake may be conducted as before stated. It requires double the quantity ol ehlorine water to destroy the colour ofa decoction of madder, than what is necessary to effect the same change in a decoction of an equal weight of Brazil wood ; a fact necessary to be observed in our own experiments on these substances. The red colour- ing matter of madder is soluble in alcohol, which re- mains when the alcohol is evaporated. In a decoc- tion of madder, the fixed alkalies produce a violet colour; and sulphuric acid a fawn coloured, and sul- ( *19 ) pliate of potash, a red precipitate. Sundry saline substances produce different coloured precipitates. As to the reagents, by which the purity of madder and carmine lakes may be determined, in a conclu- sive manner, the fact of the solubility of alumina, and * the colouring matter of these substances in a concen- trated solution of potash or soda, will point out in these alkalies proper tests or solvents. ROSE PINK. This is a preparation of Brazil wood, made by throwing into a decoction of that wood a quantity of clialk, together with a solution of alum, to which some potash is added. It is nothing more than the colour- ing matter of the wood, precipitated by the alumina. and absorbed by the carbonate of lime. The quan- tity of chalk is, therefore, variable. The proportion of colouring matter, thus absorbed, may be, if neces* sary, readily ascertained. ROUGE. Although carmine is usually sold and used as rouge, which is the most expensive of the two, yet rouge, properly speaking, is a preparation of the flowers ©f the rurrfiamus tinctorius or safflower. The washed flowers are digested in a solution of carbonate of so- da, which takes up the red colouring matter, which is precipitated by the addition of lemon juice. The precipitate is then u ,»^hed, dried, and mixed with a portion of powdered talc, or French chalk. ( 220 ) The .colouring matter of rouge should be wholly soluble in alkali. What remains is either talc, or soioe other foreign substance. Speaking of the col- ouring matter ofthe carihamus we may add, that it is of two kinds, red and yellow. The yellow is rea- dily extracted by water. The red, however, is em- ployed by dyers. It has a stronger attraction for cotton than the yellow; and even in the dyeing of cotton, in consequence of that affinity, the two pig- ments are separated. VERMILLION. There are two sulphurets of mercury; the black and red. Vermillion is the red sulphuret, which is the same as a fictitious cinnabar, but made into an impalpable powder. The black sulphuret, or ethiops mineral, is called the protosulphuret of mercury. When mercury is added by degrees to its own weight of melted sul- phur, and the mixture constantly stirred; or when one part of mercury and two parts of sulphur, are tri- turated together in a mortar, the black sulphuret will be formed. When this is heated red hot in proper vessels, cinnabar, or the red sulphuret, will be sub- limed, which, when reduced to fine powder, takes the name of vermillion. Vermillion, on account of its price, is frequently adulterated, either with red lead, carbonate of lime, or dragon's blood. Its adulteration with red lead is particularly injurious, as it is often used to colour ( **1 ) <«iigar in confectionary, and for other purposes. If it be amii'eraied with the red oxyde of lead, its detec- tion may be atiernpted by digesting it in acetic acid, aid adding to the solution water containing sulphur- etted hydrogen gas, which will occasion the well known brownish black precipitate. If this precipi- tate be collected, and exposed to the action of the blow pipe on charcoal, metallic lead will be obtained. The pt(o<"tce of carbonate of lime may be known by acetic acid; the effervescence will ensue, and the solution when tested with oxalate of ammonia, will gi/e an oxalate of lime. The presence of dragon's blood is recognised by alcohol, which will pro- duce a blood red tincture. Alcohol has no effect on pure vermillion. RED LEAD. Lead unites with oxygen in three proportions, forming the protoxyde of lead, which is yellow; the peroxyde which is brown; and the red ox- yde, or red lead, which appears to be a compound of the yellow and the brown. When lead is melted, and exposed to the air, a pellicle forms on its sur- face, and the lead gradually becomes converted into an oxyde ; or if this powder be exposed to further heat, a greenish yellow powder will be produced; and if this powder be exposed to heat some time longer, in an open vessel, it absorbs more oxygen, assumes a yellow colour, and is called massicot. If massicot be put into a furnace, when pulveris- 19* ( 222 ) ed, and the flame be allowed to play upon it, in a properreverberatory, constantly stiring it, at the ex- piration of 48 hours it will be converted into a beau- ful red powder. This powder is minium or red lead. Red lead is a tasteless powder, of a deep red co- lour, and very heavy ; its specific gravity being 8. 940. It is composed of Lead, 100 Oxygen, 11.08 The per oxyde of lead, which is ofa brownish colour, contains by weight Lead, 100 Oxygen, 15.384 The prot or yellow oxyde is composed of Lead, 100 Oxygen, 7.692 The red oxyde of lead may be adulterated with red ochre, or some cheap colour of \hat kind. Such additions, however, diminish its specific gravity.— The addition of water to the lead, and stirring it re- peatedly, will, ia a great measure, prove this fact. The red lead being a much heavier substance will subside first, leaving the ochre in suspension. The ochre, however, may be recognised by a few simple experiments. With respect to the coarser red pigments, as red ochre, light red, Venetian red, he. with Spanish brown, they are seldom if ever adulterated. A kind of factitious red chalk has been made »f red lead, crocus martis, &c. mixed with clay, and baked to a ( *™ ) Uertain degree. But as red chalk is merely colouied by oxyde of iron, as it is found in the earth, the pre- sence of red lead, if its detection is attempted, may be effected by the rules already given. Terra Sienna, a brown ochre of an orange cast, is used by painters both in its raw and burnt state. When burnt, it acquires a deeper colour, owing to the oxydizement of the iron it contains. It is some- times mixed with other browns.* YELLOW PIGMENTS. Chromic yellow is a beautiful yellow paint. It is composed of chromic acid and oxyde of lead. Chromate of lead has been made in some consid- erable quantity in the United States. The ore from which the chromic acid is obtained, is an ore of iron, usually, though we think improperly, called the chro- mate of iron, for the chrome does not seem to be Originally in the state of chromic acid. The ore, however, is pulverised, mixed with nitrate of potash, and the mixture exposed to a strong heat in a cru- cible; chromate of potash is thus formed, which * Boles are viscid earths, more friable than clay, but less co- herent. They are soft and unctious to the touch. The principal boles are the following: Armenian bole, of a bright red colour with a tinge of yellow ; French bole, ofa pale red colour, variegated with specks of white and yellow; the bole of Blois, which is yellow, and lighter than the common yel- low ochre; Bohemian bole, also yellow with a tinge of red ; Lem- nian earth, of a palish brown; and Silesian bole, of a pale yel- low colour. All these boles when exjiosed to heat change their- ( 224 ) is dissolved in water. This solution is then added to acetate of lead; a double decomposition tci-.es place, and chromate of lead is precipitated, which is washed and dried. True chromic yellow should not effervesce with nitric acid. Genuine chromate of lead, according to Thomson, is soluble in the fixed alkalies without decomposition. Nitric acid also dissolves it; but muriatic and sulphuric acids decompose it, precipi- tating the lead in the state of muriate or sulphate.— According to Brande, however, when potash or soda in solution is digested on chromate of lead, an cr- ange-coloured solution of the alkaline chromate is formed, which, when treated with sulphuric acid and evaporated, furnishes crystals of chromic acid.— Here is certainly a contradictory opinion. If the fixed alkalies dissolve chromate of lead without de- composition, the alkali must merely act as a solvent of the pigment; but if they decompose chromate of lead, forming thereby an alkaline chromate, the ox- yde of lead must remain at the bottom. By treating the alkaline chromate with sulphuric acid, a sulphate of alkali is formed, while the chromic acid is pre- cipitated. The use of nitric acid, as a solvent of chromate of colour. When made into little masses, and stamped with cer- tain impressions, they are called terra sigillatie. True bole, if it be immersed in water, after it is fully dried should fall asunder with a crackling noise. A piece put on the tongue soon falls to pieces, impressing a slight sense of astrin- gency. Bole is often found in Wacke and basalt, as in Silesia, Hessia, and Sienna in Italy, and in the clifts of the Giant's Causeway, Ireland. It has been found in the United States. ( 225 ) fead, an.I of sulphuric and muriatic acide as precipi- tants ofthe lead, as above stated, furnish the best proofs ofthe purity of this pigment. The several yellows, as Indian yellow, a prepara- tion of chalk with fermented urine ; king's yellow, a pieparation of orpiment;patent yellow, a fused sub- muriate of lead ; Naples yellow, a preparation of lead and antimony; yellow ochre, an earth coloured with oxyde of iron ; massicot, the yellow oxyde of lead ; Dutch pink, a preparation of French berries and chalk, he. are seldom adulterated. But the presence of the vegetable colouring matter of turmeric itself, m-iy be detected by an alkali, to which it will im- part the well known brownish red colour. Gam- boge, if suspected in any of these pigments, will show itself on the addition of alcohol. A-yellow pigment may be obtained from the agri- mony (ngrimonia eupatori,) as well from its leaves and stalks as from its closed flowers, by making a decoction, and adding a diluted solution of bismuth. A water colour, called weld yellow, much used by paper hanging manufacturers, is the colouring matter of weld precipitated with an earthy base. For the preparation of this pigment, whiting and alum are mixed with water, and boiled together,; then a strong decoction of weld is made, and poured on the whi- ting and alum ; and after boiling the whole for a few minutes, it is poured out, and dried. PRl SSIATE OF COPPER. This pigment is ofa chocolate brown, and has late- ( 226 ) ly been introduced as a good colour of that description. It is, however, expensive, and adopted only as a water colour. It is prepared by Mr. Hume ol London, by d- composing the sulphate of copper by the leirocy- anate of potash. It is, therefore, a ferrocyanate of copper. It should be entirely free from sulphate of potash, and when digested in caustic potash be com- pletely decomposed, leaving an oxyde of copper. When exposed to the blow pipe on charcoal, it is decomposed, and the copper reduced. The most perfect brawn is produced when the copper is oxydized to the maximum ; hence the per salts of copper should be preferred. The precipitate should be well washed to separate the sulphate of potash. In consequence of the precipitation of cop- per of a brown colour from its solutions by ferrocya- nate ol potash, the latter has been recommended, and is used as a reagent for copper. If the per oxyde be combined with the ferrocyanic acid, the pigment must be the per ferrocyanate of copper. In the preparation of Prussian alkali (ferrocyanate of potash,) in order to obtain it free from any ferro- prussiate of iron, which it holds in solution when prepared in the usual manner, Dr. Henry first sug- gested the use ofthe ferrocyanate of copper. This is digested in a solution of pure caustic potash.— The prussiate of potash, as it was formerly called, which is thus prepared, is a purer preparation for a test than that formed by digesting a solution of pot- ash on the perferrocyanate of iron. LECTimis, iv. BROWN PIGMENTS. Several of these colours are liable to adulteration. Thus bisire, which is the carbonaceous basis of wood soot, collected in the chimney, after having been washed in water to separate any pyroligneousacid or immoniacal salt, should be entirely free from burnt timber. If it contain umber, or other incombustible substance, it may be proved by exposing it to heat; pure bistre will entirely consume, without leaving a- nv earth v or metallic residue.* Ofthe other browns * Wood-soot contains several substances, and what is rather remarkable, a lur^e proportion of pyroligneous acid, which we have noticed under the head of Wood vinegar. The quantity is Miirieient to preserve meat; for on making a mixture with water, in due proportions, the water will unite with the empy reumatic acid, i. e. the pyroligneous acid containing empyreu- matic oil, which has been successfully applied to that purpose. This fact « e deem worthy of repeating, as soot can be had at any time, whereas wood vinegar must be prepared from wood by distillation. No doubt, however, but the infusion of -t in water, also contains a portion of ammoniacal salt. Soot, ( 228 ) Cologne earth, umber, asphaltum, and brown pink, little need be said. The Cologne earth is often spu- rious. It is prepared from an earth found in the neighborhood of Cologne; but as earths which con- tain iron, may be burnt of a certain colour, according to the heat, the imitation of true Cologne from light brown earths has been attempted. The earthy lignite found near Cologne, in beds of from 20 to 30 feet thick, is sometimes called, and u- sed for Cologne earth. Its colour is nearly black, or blackish brown, and is but little heavier than water. tt is known, however, from the real Cologne earth by its combustibility. It burns like tinder, with little or no flame. ' It often containspj'rites, and then fur- nishes alum, and passes into aluminous eatth. Al- um is manufactured in the LTnited States from pyri- tous lignite. See Allum. Asphaltum, if adulterated with earthy substances, may be examined with oil or spirit of turpentine. As it is a solid bitumen, and wholly soluble in turpen- itis known, was formerly the basis of an officinal preparation, called the tincture of wood-soot. The carbonaceous part of wood-soot, whirh forms the pigment above mentioned, is ofa brown colour ; and by the repeated ablutions of water, the sa-, line matter, as well as the pyroligneous acid, kc. are separ- ated. The soot from vegetables, the formation of which al- ways indicates an imperfect combustion, (as stoves have been ■>o continued as to burn their own smoke,) differs from the soot of animal substances. O f this fact we have an instance in the former preparation of sal ammonia. In Egypt, where sal am- moniac was originally made, camel's dung is used asfue»-the *oot of which was collected, and sublimed. By this operation ( 229 ) tine, any foreign admixture may be thus detected. Asphaltum, as a colour, is affected considerably by the temperature. It is of great antiquity, and is said to have been the cement used by the Egyptians, and for the purpose of pitch. Brown pink is a paint of little durability, but should be entirely free from umber. Its preparation consists in impregnating chalk with a decoction of fustic, the colour of which being heightened by the addition of potash. This colour is liable to change by acids, as the acids act on the colouring matter of the fustic. BLACK PIGMENTS. Ofthe black pigments, especially those employed for water colours, none presents such a diversity of character as Indian ink. This is owing to the differ- ent modes of preparing it. Some have supposed it to be a preparation ofthe gall ofthe cuttlefish; this, however, is an error. It is ascertained by experi- ment, that lamp-black forms the basis of this ink, but the muriate of ammonia was separated from the other substan- ces ; but, before it could be used, it was usually resublimed.— See Sal Ammoniac. The painful sensation on the eyes produced by ordinary smoke is well known; this is attributed to the pyroligneous acid. That smoke contains a large quantity of moisture, or vapour, derived from the wood, especially if it be green, is very appa- rent of a frosty morning; it appears more thick and dense, which is owing to the pat tail condensation of the vapour by thr abstraction of caloric. 20 ( 230 ) that it is remarkably fine, and free from any oil or turpentine. The soot that constitutes lamp-black va- ries in quality according as it is obtained from tar, tur- pentine, or oil. The best and finest lamp-black is prepared by the combustion of oil; and in the small way, by collecting it in a tin funnel over a lamp : it will be found decidedly superior to the ordinary lamp-black. The quality of lamp-black may be improved by heating it at a given temperature, on a plate of sheet iron, or exposing it to heat in a covered crucible. To prepare Indian ink, a due quantity ofthe fine lamp- black is to be mixed with size or animal glue. Sev- eral recipes, however, are given. Indian ink may be examined by dissolving it in water, and filtering the solution. The water holding the gelatin in solution, if sufficiently diluted, will pass through the filter, leaving the atramentous mat- ter, which may be examined for charcoal, he. The lamp-black should burn entirely away, without leav- ing a residue, and when thrown on ignited nitre in a crucible produce a deflagration. The gummy fluid may be tested either for gum or gelatin ; for the for- mer by silicate of potash, (liquor of flints,) and for the latter by a solution of tannin. All the Indian ink imported into the United States, does not come from China ; a large quantity is made in England. The English, however, is coarse, rough, and gritty, and generally has a blueish cast. The Cashew nut, we may remark, furnishes a native black coiour. See Lac. ( 231 ) Lamp black ought to be the soot of oil, but is notv the soot of tar, turpentine, dregs of pitch, pine knots, he. which is inferior in quality to the first*. The ordinary lamp black may be improved either as be- fore stated, or by heating it in confined vessels, which certainly gives it a more perfect blackness. We do not recollect of any fraudulent adulteration of lamp black. It should, however, when burnt, be en- tirely consumed, without leaving any residue; and alcohol digested on it should not extract any tur- pentine, or rosin. It ought to be free from grit and feel impalpable between the fingers. What is called ivory black in the shops is not the carbon of ivory; which, being remarkably compact, furnishes a dense compact coal; but that which is sold is the ordinary bone black, an animal coal much inferior to the true ivory black. In fact the latter is scarce and costly, whereas the bone black is plenti- ful ami cheap. The perfection of this colour, de- pends on the due carbonization of the bone. The gelatin ofthe bone appears to be the principal sub- stance which is carbonized. Bones when burnt to ashes, furnish phosphate of lime, a substance which has been used in painting, and for other purposes. Ivory black may be mixed with charcoal. la the operation of grinding carbonized bone, which is performed in a mill, a due proportion of charcoal, we have known to be added, and the whole ground together, and sold as ivory black; a name, however, given by usage to bone black. As the two ( 232 ) ooais is a mechanical mixture, that of the animal be- ing heavier than that of the vegetable, when they are thrown into water, the latter will swim while the for- mer will gradually subside. Ivory black containing charcoal readily takes fire, a circumstance attributed to the vegetable coal. The quantity of charcoal, however, is variable. If some of this mixed black be projected into an ignited crucible containing ni- trate of potash, a deflagration nearly as brilliant as if charcoal alone were used will ensue ; and if nitric acid be poured on, it will furnish, especially if the coal be previously heated, an abundance of deutox- yde of azote, along with carbonic acid gas. A min- eral black, called black chalk, is also used as a co- lour. This native chalk is an intimate mixture of carbon, silica, and alumina. The blue black is a vegetable coal. It is prepar- ed of the best quality from vine stalks, carbonized in a covered crucible, or iron cylinder. PURPLE PIGxMENTS. Of these the ordinary crocus martis is the most common. It is a preparation of iron, and is liable to be adulterated with colcothar of vitriol. If the crocus martis is the saffron coloured oxyde of iron, and answering to the red oxyde in its quantity of ox- ygen, and colcothar of vitriol the same as the per oxyde of iron, there can be no difference in the com- position of the two; but notwithstanding they are thus identified by Dr. Ure, the calcined copperas or ( 233 ) colcothar is altogether different from the red or per- oxyde of iron. All the sulphuric acid is not disengaged in the preparation of colcothar, however the iron may be oxydized to the maximum ; and, therefore, the sub- stance which remains after the calcination of vitriol, is in fact a subsulphate of iron. As pigments, how- ever, they may be used alike; but when employed for the polishing of metals, every artisan, or work- man, will give the preference to crocus. Crocus martis besides being mixed with the sub- sulphate of iron, is frequently adulterated with red ochre, and red lead. The detection of these sub- stances may be effected by the processes already given. A purple lake may be prepared from log- wood,—by making a decoction ofthe wood, and ad- ding the muriate of tin. The muriate of tin precip itates the colouring matter of a purple colour. The purple powder of Cassius, although not era- ployed as a pigment in the proper acceptation of the term, is much used in enamel painting, and for ting- ing glass of a fine red colour. It is prepared by precip- itating muriate of tin with, or by immersing a piece of tin in a solution of gold. It is composed of per- oxyde of tin and oxyde of gold, in the proportion of about three parts of the former to one of the latter. The purple of Cassius when digested in nitro-muri- atic acid should be decomposed, and the gold taken up, while the tin remains; and muriatic acid ought to dissolve the tin, and leave the gold. In amuio» 20* ( 234 ) aia it is soluble, forming a deep purple liquor. See Artificial Gems. The gold powder for painting is a preparation of gold leaf. The best process for making it, consists in triturating the leaves of gold with a little clear ho- ney : and when the gold is sufficiently divided, wash off the gold with water. The powder is then to be digested for a few minutes in muriatic acid, perfectly pure, and the acid removed by repeated ablutions with rain water. Pale gold powder may be prepar- ed in a similar manner, from gold alloyed with sil- ver. Silver leaf, treated in a similar way, furnishes silver powder. The purity of gold powder m; y be known by its being wholly soluble in nitro-muriatic acid, and by its precipitation in a metallic state by the protosulohate of iron. If any residue should be left it may be examined. Silver powder should be soluble in nitric acid, and the silver precipitated by copper; or the precipitate obtained by muriate of soda, should be wholly soluble in liquid ammonia. Silver powder has also been prepared, by precipita- ting silver from its solution by a plate of copper. A gold powder for gilding silver without heat, has also been made by soaking linen rags in a concentra- ted solution of muriate of gold, drving them, and set- ting them on fire. The ashes contain minutely di- vided gold and charcoal. Gold precipitated from its solution in aqua regia, by the green sulphate of iron, may be used for the same purpose. Gold powder is also made by amalgamating gold with mercury; separating the extraneous mercury by ( 2^ ) squeezing the amalgam in a fine muslin ; and the mercury from the gold by diluted nitric acid. The gold will remain in powder. Shell gold and shell silver are the same as gold and silver powder, only mixed with gum and put into shells. The aurum moscaium, or Mosaic gold, which is used in some of the ornamental arts, is the persul- phuret of tin : it is prepared by subliming a mixture ol 12 parts tin, 7 parts sulphur, 3 parts mercury, and 3 parts sal ammoniac. When pure, it is in the form of light scales, which have the colour of gold, and readily adhere to other bodies. The same compound may lie formed, by heating the per oxyde of tin with its weight of sulphur. li .sides being used as a pigment for giving a gold- en colour to small statue or plaster figures, he. it is also said to be mixed with melted glass to imitate lapis lazuli. Wiieu pure, and exposed to heat, a part of its sul- phur is separated, and is converted into common sul- pimret ot tin, which has a lead colour. Another ch-iracter i-, that it is soluble in a solution of potash assisted by heat, the solution having a green colour, from which a yellow powder (hvdrosulphuret of tin, according to Proust,) is precipitated by the addition of an acid. GREEN PIGMENTS. Of thA class of pigments, some of the preparation^ ( 236 ) J copper are particularly noted.* Seheele's green is a compound precipitate, of arsenious acid and ox- yde of copper, and is formed by mixing arsenite 01 potash with sulphate of copper. The precipitate should be well washed to separate the sulphate of potash. If the sulphate be contained in it, the fact may be known by digesting a portion of the pig- ment in water, and filtering the fluid; then, by ad- ding to separate portions, muriate of barytes and tar- taric acid, we discover both the sulphuric acid and potash. If if be mixed with carbonate of copper, an acid will cause an effervescence, and the solution may be examined as in other similar cases. If car- bonate of lime be suspeoted, the solution may be ex- amined for that earth. An excess of acid, it will be observed, will take up both copper' and hme; hut lime will decompose a cupreous salt. Verdigrease is the most common, and at the same time the most valuable of the cupreous pigments. It is copper corroded by the action of grape stalks, *The salts of copper are recognised by the following propef- ties : They are almost all soluble in water, or become so by the addition of an acid, the solution having either a blue or green colour. Ferrocyanate of potash produces a chocolate brown, especially with the persalts. Hydrosulphuret of potash gives a brownish black precipitate. Gallic acid a brown precipitate.— A plate of iron precipitates the copper in a metallic state.— See the Detection of copper, in a preceding lecture. The salts of copper, when heated before the blow pipe, give a fine green flame. The oxyde of copper with microcosmic salt and borax, forms a yellow green glass while hot, but which becomes blue green as it cools. ( 23r ) refuse of grapes, he. It is called the green oxyde, or subacetale of copper. The amount ofthe admixture of impurities in ver- digrease may be learnt, by digesting one part of ver- digrease in twelve parts of distilled vinegar lor some time, suffering it then to stand, and collecting and weighing the insoluble part. The acetate of copper may be evaporated and crystallized. Should the verdigrease contain sulphate of copper, it may be known by boiling it in water, and evaporating the solution. Crystals of acetate of copper will first se- parate, and afterwards those of the sulphate of cop- per. Muriate of barytes will detect the sulphuric acid. If tartrate of copper should be present, it may be known by dissolving a portion of the verdigrease in distilled vinegar, and adding to the solution muri- ate of barytes, which will produce a white precipi- tate soluble in muriatic acid. The French verdigrease, according to Phillips, (A inals no. 21,) contains 43.5 per oxyde of copper. and the English 44.25. The crystallized verdigrease, or crystallized ace- tate of copper, a salt which is formed by dissolving the common verdigrease in distilled vinegar, and crystallizing the solution, should, if pure, be entirely soluble in six times its weight of boiling water, and the solution not affected by muriate of barytes. A precipitate occasioned by the latter is an indication of the presence of sulphuric acid. Sulphate of cop- per may be recognised by crystallization. It seems according to the British Journal of Sci- ence, no. xxvu. that before verdigrease is pressed ( 238 ) into cakes, it is in the form of light blue acicular crystals of a silky lustre, which, by the action of wa- ter, are resolved into a soluble acetate, and an insol- uble subacetate of copper, the latter being decom- posed by cold water, which changes it to a brown colour. ?dr. R. Phillips, (Annals no. 21,) who made these researches, has not ascertained whether the verdigrease is thus resolved into oxyde of copper, or remains as a sub salt, The process used at the present day for the man- ufacture of verdigrease, is the same as that which was employed in the time of Theophrastus, Dioscori- des, and Vitruvius. Every green oxyde, however, was comprehended under the name of cerugo. Profess- or Beckman, who has examined this subject with his accustomed accuracy, in speaking of the explanation of verdigrease, remarks: " The ancients for this pur- pose, used either vessels or plates of copper, or only shavings and filings; and the acid they employed was either the sourest vinegar, or the sour remains left when they made wine : such as the grapes be- come sour, or the stalks and skins after the juice had been pressed from them." He mentions also the exposure of copper to the vapour ofthe acid, in the same manner as Theophrastus describes for the cor- roding of lead, in making white lead, a practice pursued in modern times. The adulteration of verdigrease was also common ; for it appears the ancients frequently adultera- ted it with stones, particularly pumice stones reduced lo powder, and sometimes with copperas. The cop- ( 230 ) peras they detected by roasting the verdigrease. which become red. The greater part of the verdigrease in ancient times was made in Cyprus, which was celebrated for its copper works, and in the island of Rhodes. The vermicular verdigrease was no other than ver- digrease united with gum, and drawn into threads like worms; a practice censured both by Pliny and Dioscoredes. For the same reason the Italians gave the name of Vermacelli, which we noticed heretofore, to'wire drawn paste of flour and egg'; used in cookery. The pigment called Brum wick green, is usually prepared by digesting copper in a solution of muri- ate of ammonia, by which the metal becomes gradu- ally corroded; or, according to another process, di- gesting the oxyde of copper, in a solution of super- tartrate of potash, by which the tartrate of potash- and-copper is formed. Leonardi observes, that this triple cupreous salt constitutes the better kind of Brunswick green. It is largely adulterated with both whiting and cerusse. The former is known, first by an effervescence on the affusion of acid, and secondly by testing the solution for lime. Cerusse or white lead is recognised by treating a solution in acetic acid for lead, as before mentioned. Sap green is a vegetable pigment, obtained from the juice of buck thorn berries (rhamnus catharticus,) by inspissation. Like the syrup prepared from the same juice, which is used in medicine, it is frequently adulterat- ed. Mr. Accum assures us, that the sirup of buck- ( 240 ) thorn berries, instead of being made from the real berry, is prepared by English apothecaries from the berries of the buck thorn, and black berry bearing alder, and of the dog berry tree ;. and that a mixture of these two berries are exposed for sale by the ven- ders of medicinal herbs. This abuse may be disco- vered by opening the berries : those of the buck thorn have always four seeds; ofthe alder, two; and of the dog berry, only one. The buck thorn berries bruised on paper, stains it of a green colour, while the others do not. The pigment, therefore, which should be nothing more than the pure colouring matter of the buck thorn ber- ry, may in like manner be adulterated. The same colour, sold as sap green, has been pre- pared from the flower of the blue lilly. It is extremely difficult to detect colouring matter, die character of which is not well marked, and when nearly allied ; but as verdigrease is often mixed with sap green, its presence may be easily shown by the use of ammonia. WHITE PIGMENTS. The genuine^a&e white, or majistery of bismuth, is frequently adulterated with cerusse or white lead. It is used as a cosmetic, but is apt to blacken like lead by sulphuretted hydrogen gas.* It should be * Cosmetics, of either bismuth or lead, injure the skin, and- are blackened by hepatic gas. Waters, for instance, which are decidedly hepatic, have been known to produce this effect when ( Z" ) entirely free from lead. There are several white pigments, some of which are of a much cheaper and coarser kind; thus Spanish white, which is chalk pulverised and washed; egg shell white, and oyster shell white, calcined hartshorn ; glass white, he.— But of the white pigments, white lead, called the white oxyde and carbonate of lead, and ceruse, is the most liable to adulteration. White lead is properly a compound of the yellow, or protoxyde of lead and carbonic acid. It is pre- pared by rolling leaden plates spirally so as to leave a space of about an inch between each coil, and placing them vertically in earthen pots, at the bottom of which is some good vinegar. The pots are to be covered, and exposed for a length of time to a gentle heat either in a sand bath, or, as is more usually the practice, by bedding them in dung. The vapour ofthe vinegar, assisted by the oxygen which is present, corrodes the lead, and converts the ex- ternal part into a white substance, which comes ofi' in flakes, when the lead is uncoiled. The plates are thus treated repeatedly until they are corroded through. The flakes are then ground in a mill, and the powder for particular purposes washed. they have been used ; bathing in them, or the gas coming in con- tact with the body, will immediately effect this change. Such instances have occurred, to the no small mortification of the ladies who employed them. To obviate this effect, chalk, fine white clay, or Spanish white, is now substituted; the practice however, ot painting, as it is called, is confined to a few. It is an ancient custom ; but its antiquity, in our opinion, is no ar- gument for its continuation. 21 ( 242 ) Lead when exposed to the action of air and water will gradually oxydize, absorb carbonic acid, and become white lead. Hence water kept in leaden cisterns contracts lead ; for the water line, where the water and air come in contact, is crusted with a white substance. See the effects of lead on water, Lecture i. The most common substance with which white lead is adulterated is chalk, next to which is the carbonate and sulphate of barytes, and sometimes sulphate of lead. Solution in acetic acid with effer- vescence, and adding oxalic acid, or oxalate of am-; monia will show the presence of chalk ; and sulphate of soda, to a portion of the same solution, will indi- cate barytes, by forming an insoluble sulphate. If any residue should occur after the acetic acid ceases to act, we may infer the presence of sulphate of lead or sulphate of barytes. The quantity of lead contained in cerusse may be readily ascertained, either by reduction with char- coal in the usual manner, or by solution in an acid, and the metal precipitated. In fact, it may be exa- mined in the same way as the native carbonate of lead'. For this purpose introduce 134 grains into a sufficient quantity of nitric acid diluted with about two parts of water; an effervescence will ensue, and the carbonic acid may be estimated by the loss of weight, which, if the statement of Brande be correct. should be in the above quantity 22 grains. Filter the solution, and if there be any insoluble residue. wash, dry, and weigh it, and set it aside for further ( 243 ) examination. By deducting this weight from 134 grains, deducting 22 for the carbonic acid, its quantity will be known. To the filtered solution add sul- phate of soda, which will throw down sulphate of lead. It consists of one proportional of sulphuric a- cid, equal to 40, and one proportional of oxyde of lead, equal to 112, whence the oxyde may be dedu- ced. But the easiest method is to separate the lead in its metallic state from the nitric solution. For this purpose immerse a plate of zinc, which will precipi- tate metallic lead, the zinc taking the place of the lead, forming a nitrate of zinc. The quantity of metallic lead in 134 grains of the carbonate, deduct- ing 22 grains for the carbonic acid, will be about 103.04 grains; deducting also the quantity of oxygen in 112 grains of the yellow oxyde of lead, which ex- ists in the white lead. The proportion of oxygen, according to Bezelius, is nearly 8 percent. It is sufficient to know, ho-vever, that genuine white lead should be entirely soluble in acetic or ni- tric acid. The residue in the above experiment may, never- theless, be boiled in a solution of carbonate of potash, the fluid then filtered, and examined for barytes or lead, and the residue again treated with acetic or ni- tric acid. The artificial sulphate of barytes is em- ployed as a pigment tinder the name of permanent tvhitc.* * Water-colours, as 7?«rf >s, are nothing more than the pig- ments we have mentioned, ground impalpablv fine, and mixed with weak isinglaf* size, or strong gum water, and formed into ( 244 ) ALLOYS OF COPPER. As some ofthe alloys of copper are important, a general notice of them may be useful. With arse- nic, it forms a white alloy, called white copper, but cakes in oblong square moulds, in which they receive certain or- namental impressions, the maker's name, coat cf arms, Uc.— They have been made up in boxes in this country, according to the English mode. The same colours mixed with gelatinous or mucilaginous matter, are often sold in shells. But the water oolours prepared by the Chinese, in small china pots and ar- ranged in a portable chest, with folding doors, accompanied by the utensils for mixing the colours, are generally superior to the English. The goodness of water colours depends, of course, on the purity of the pigments, their pulverization into an impal- pable powder, and their mixture in due proportions with gum- my matter, which not only serves to unite the particles togeth- er, but also when mixed with water, and applied with the brush, to prevent the colour from rubbing off. Oil colours, on the con- trary, are mixed with drying oil, and are used chiefly for coarse work, as house-painting. Dryed oil is a preparation of linseed oil, made by boiling the oil with litharge, which separates a quantity of mucilage from the oil. Spt. of turpentine is usually added to thin the paint and facilitate its drying. Nicholson (Mechanical Exercises, p. 319.J gives the follow- ing list of useful colours for house painting : Black—lamp black. White—white lead. Yellow—ochres, also patent yellow. Blue—Prussian blue, and blue black. Red—red lead, vermillion and purple brown, or India red. ------crimson, lakes, to which add vermillion, or white ac cording to the tone. Green—grass, verdigrease. ------invisible, dark ochre, blue and a little black. Green—a good, patent yellow and Prmsian blue. —----- pea, mineral green. ( 245 ) more properly white tombac, in which, however there is usually a little tin or bismuth : with zinc or spelter it forms brass, the proportion of the metals being variable, as in English brass there is 1.3d of zinc, and in German or Swedish, from 1.5th to 1.4th of copper; hence in English hrass the alloy will consist of two parts of copper by weight, and 1.8th, part of zinc, equivalent to one atom of each metal, but in Dutch brass the compound is 2 atoms copper Chocolate—India red and black. Lead colour—black and white. Brown—umber, raw and burnt. -------mix black, red, and dark ochre. Purple—mix lake, blue, and white. Yellow and red make an orange colour; red and blue, a pur- ple and violet; blue and yellowy green ;light ochre, Prussian blue, and a little black, an olive; India red and white, a flesh ; white and umber, a stone ; and black, blue, white, and a little India red, a peach colour. SirH. Davy (Phil. Trans. 1815,) made some interesting ex periments at Rome on the colours used by the ancient artists. He found the reds to be minium, ochre, the yellow orpiment and massicot; the blues, formed from carbonate of copper, or cobalt, vitrified with glass; the purples, made of shell fish, and probably from madder and cochineal lakes; the blacks and browns, lamp black, ivory black, and ores of iron and manganese; and the whites were chalk, white clay, and cerusse. Various pig- ments, but principally echres, were found among the niins of* Herculaneum and Pompei. They bad regular paint shops.-— See Bartholemey's Travels, fac. A.s to the great durability of pigments, as some are known to have preserved their original colour for 1700 years, it de- pends entirely on their basis. Coloured frits, or glasses, are unquestionably the most indestructible, as Sir H. Davy ascer- tained by his experiments. 21* ( 240 ) and 1 atom zinc. With zinc also, it gives rise to pinchbeck, Prince's metal, Prince Rupert's metal, he. the proportion of zinc sometimes amounting to nearly one half of the whole: the ancient orichal- cum was also an alloy of the same metals. With tin it unites in variable proportions, forming gun metal, bell-metal, bronze, and the mirrors of telescopes, the ductility ofthe copper being diminished, while its hardness, tenacity, fusibility, and sonorousness are increased. Bronze and gun metal are composed of from 8 to 12 parts of tin and 100 parts of copper, which is the same alloy used by the ancients for sharp edged instruments before the method of work- ing iron was brought to perfection : brass guns, im- properly so called, made at Woolwich, England, are composed of from 8 to 1% parts of tin, to the 100 of copper; the purest copper requiring the most, and the coarsest the least. This also is more sonorous than iron; hence brass guns give a much louder re- port than those made of cast iron. Bell metal is an alloy of 3 parts of copper and one ^>art of tin ; but the proportion of tin varies, as less tin is used for church bells than clock bells, and in small bells as those of watches, a little zinc is added to the alloy. The conch of the East Indians is composed of tin and copper, in the same proportions as in bell metal.— The speculum metal of the ancients, was composed of 2 parts of copper, and 1 part of tin; but Mudge's composition is 32 parts of copper, and 14.5 of tin: Copper, will also unite with tin, in the operation of tinning, 21 grains of the latter being sufficient t© ( m ) cover a pan lJ inches in diameter, and 3 inches three lines in depth; more than this will melt off. When copper plates are cemented with calamine, (an ore of zinc.) they are converted into a fine kind of brass, which is hammered out into leaves in Germany, and sold under the name of Dutch gold, or Dutch metal. Ancient daggers, like their cutting instruments, were composed of copper and tin, in the proportion of about 83 ofthe former to 10 of the latter: some of the ancient coin was also made of copper with the addition of a small quantity of tin; but in the forma- tion of their brass, which they much valued, they used an ore of zinc called cadmia. The ancients, in their writings, frequently confound as the same, copper, bronze, and brass. Tutenag is gaid to be an alloy of copper, zinc, and a little iron. Jewelry trinkets are alloys of gold and copper, in which the proportion ofthe copper to the gold is va- riable, and sometimes so great that they ought to be placed under the alloys of copper. Copper renders gold less ductile, harder, more fusible, and of a deep- er colour. This is the usual addition in coin; but for the purposes of coin, Mr. Hatchett considers an alloy of equal parts of silver and copper preferable. A fifth part of silver renders gold greenish; the com- pound is always paler in proportion to the quantity of silver added. A pale greenish yellow gold, is formed by uniting 11 parts of gold to 1 of zinc. Gold coin, sterling or standard gold is a mixture of pure gold with 1.12 of some other metal. The metal us- ed i-s always either copper or silver, or a mixture of ( 248 ; both. In British coinage, a pound of standard gold is coined into 44 1-2 guineas, or 20 troy pounds are coined into 934 1-2 sovereigns. In expressing the fineness of gold, the whole mass is supposed to weigh 24 carats, of 12 grains each, either real or propor- tional, so that gold of 23 carats fine implies a mass weighing 24 carats, and the quantity of pure gold 23 carats. This alloy of gold and copper, constituting jeweller's gold, varies in the number of carats of pure gold : gold of 12 to 18 carats fine, is the kind most- ly employed for trinkets, watch chains, he. Green gold of the jeweller's, is usually an alloy of gold and silver. Having noticed in a cursory manner, the principal alloys of copper, we purpose in the next place to mention briefly the several methods of examining these alloys, with the view of ascertaining the pro- portion of their constituent parts^ The alloys of gold may be examined by nitric acid; for nitric acid it is known exerts no action on that metal, whereas it dissolves copper, silver, and several other metals. Bat the analysis of mosl of the alloys of gold is performed by a process called cupellation, which consists in exposing the alloy along with lead to the action of heat, in a cupel, a vessel made of bone-ash. The lead melts, then oxydizes, and finally vitrifies; the glass of lead then unites with the foreign metals, as copper, lead, tin, he. and is absorbed by the cu- pel, while the gold not being oxydized, and there- Core not acted upon by the vitrified oxyde of lead. ( 249 ) ioniums in the vessel. Quartation is often necessary in cupellation. By knowing the quantity of alloy submitted to experiment, the loss it has sustained will indicate the proportion of foreign metals. In an alloy, however, of gold and silver, cupellation can- not be used ; but if copper, tin, bismuth, he. be in 'he alloy, these metals will be separated. To sepa- rate silver from gold, nitric acid is used, which dis- solves the former, and leaves the latter. The silver may be precipitated by muriate of soda, in the form of muriate of silver. If a triple alloy of gold, silver, and copper is to be xamined, we may digest it in nitric acid, which will take up the silver and copper, and leave the gold in the form of a black powder.. This powder may be fu ;ed into a button and weighed. The copper may be precipitated by iron, and the silver by a solution uf muriate of soda. It may be of importance, very frequently, to de- termine the proportions of copper and zinc in brass; for the relative proportions of the two metals vary in the different kinds of brass. There is usually from 12 to 18 percent, of zinc. In the formation of brass, a mixture of granulated copper, calamine, md charcoal, is exposed to heat; the calamine is re- duced, and the metallic zinc unites with the copper, and the alloy is usually cast into plates. A beauti- ful brass may be.made, according to Sage, by ex- posing to heat in a crucible 50 grains of oxyde of copper, 100 of calamine, 400 of black flux, and 30 charcoal powder. Three parts of copper and one of ainc are the proportions for Manheim gold. I 250 ) Brass may be examined in the following manner r Dissolve it in nitric acid, and add a considerable ex- cess of the solution of potash, and boil. The alkali will decompose the nitric solution, and precipitate the metals" in the state of oxydes; but, as an excess of alkali is added, the oxyde of zinc will be taken up, leaving that of the copper. Collect the oxyde of copper, and wash it; then expose it to a strong heat: 125 parts will indicate 100 of copper. To the filtered alkaline solution, containing the zinc, add an excess of muriatic acid, and afterwards carbonate of soda, which will precipitate the zinc in the state of carbonate. When this precipitate is washed, dry- ed, and exposed to a red heat, it will then be the oxyde of zinc ; 123 parts of which indicate 100 of metal. If an alloy of copper, as copper and zinc, be di- gested in sulphuric acid diluted with an equal quan- tity of water, the solution filtered, and a plate of zinc or iron immersed, the copper will be precipitated in a metallic state ; or if the alloy be digested in nitro- muriatic acid, composed of equal parts of nitric and muriatic acid, and the digestion continued till all the copper is dissolved, the solution filtered, and precip- itated by carbonate of potash, the precipitate re-dis- solved in a sufficient quantity of sulphuric acid, and the solution decomposed by a plate or cylinder of of iron, metallic copper will be obtained. This pro- cess, we may remark, was recommended by Dr. Fordyee for analysing all copper ores, and is well a- daoted for the examination of alloys of copper, for ( ^1 ) the purpose of determining the quantity of that metal. The zinc as well as the copper, is precipitated by the carbotiate of potash, and are both taken up by the sulphuric acid; therefore, after the precipitation of the copper by the iron, the solution will contain the sulphate of zinc and iron. The quantity of zinc con- tained in the alloy, which is now in the solution, may be learnt by adding liquid ammonia in excess: the oxyde of iron, as well as the oxyde of zinc, will be precipitated, but as an excess of ammonia is used, the latter will be re-dissolved. If the liquid be now filtered to separate the oxyde of iron, and exposed to the action of heat, the ammonia will be volatilized. and the oxyde of zinc precipitated; or, if we satur- ate the solution with muriatic acid, adding no more than is sufficient to neutralize the ammonia, oxyde of zinc will fall down, which may be reduced to the metallic state by igniting it with half its weight of charcoal, iu a closed crucible. If, on the addition of ammonia, the solution assumes a blue tint, it is a proof that all the copper had not been precipitated; but this tint will not be visible, if even copper be present, before the oxyde of iron is sepafated. If iron be in the alloy, as it is said to form a constituent part ofthe Asiatic tutenag, repeated digestion in ni- tric acid will render it insoluble. If the nitric solu- tion be suffered to stand undisturbed, a brown pow- der, which is the oxyde of iron, will be deposited ; this may be separated by the filter, and its quantity ascertained. By the increase of weight which copper gainf ( 252 ) when it combines with zinc, the assay of zinc ore*, has been performed. This process is exceedingly simple; the ore of zinc is first roasted, and stratified with its weight of the clippings of sheet copper, in a erucible; a cover is luted on the crucible, which is then exposed to a dull white heat for an hour; when cold, the contents are thrown into water, which sep- arates the brass from the other matter ; by weighing it, the increase of the weight of copper will be ascer- tained, which of course, indicates the quantity of zinc. In this process, however, a portion of zinc is always lost. The examination ofthe alloys of copper and tin, as bell metal, speculum metal, bronze, gun metal, he. is also important. It may be performed by digestion in nitric acid, which dissolves the copper, forming nitrate of copper, while it oxydizes, or converts the tin into an insoluble per oxyde. This per oxyde is to be collected, washed, and dried. It consists of 100 tin and 27 oxygen. To the nitrate of copper add a solution of potash, till no further precipitation takes places; collect the precipitate on a filter, wash, and dry it. It is the per oxyde of copper, and contains in 125 parts, 100 of copper. It will be observed, that these formula? are sufficient for the examination ofthe alloys of copper, and may be employed for the analysis of all compounds of that metal with gold, zinc, and tin. Thus, if we submit to experiment tutenag, we will discover a larger pro- portion of copper than zinc; and likewise more cop- ( 253 ) per than exists in brass, in the alloys that constitute yellow tombac, Dutch gold, similor, Prince's metal, Prince Rupert's metal, pinchbec, and Manheim gold, and in the latter a portion of tin, which is added to improve the colour, although it impairs the mallea- bility of the alloy. In the examination also, ofthe alloys of copper and tin, we will find the proportions ofthe two metals variable, and the copper always in the largest proportion, as in gun metal, bell metal. speculum metal, and bronze. In some of these al- loys, as in Edward's composition for speculum, we may discover arsenic ; and in some varieties of bell- metal, especially those calculated to make a shrill sound, we may detect zinc ; for that metal, however small, will greatly increase the sonorousness of the alloy of tin and copper. By conducting similar ex- periments with the ancient cutting instruments, which were used before iron came into use, ancient cop- per coin, daggers, he. all which were alloys of cop- per'and tin, we may determine exactly the propor- tions of these two metals. We might mention also the examination of the alloys of gold and copper, forming coin, gold for jewelry, Sic. for, by analysis, according to the process we have given, the propor- tion of gold may be invariably discovered. The same may be effected by weighing the alloy hydra- matically, when, by well known rules, the specific gravity may be determined, and the quantity of al- loy ascertained; formula? for which may be seen in Adam's Philosophy. It will be recollected, that it was by employing this hydrostatic principle, thatAr- 22 ( 254 ) chimedes was able to discover the adulteratiion m Hiero's crown. The specific gravity of pure gold is 19.8. As one of the methods for detecting arsenic, is to place it, or the powder supposed to contain it, along with powdered charcoal, or black flux, between cop- per plates, and expose them to the action of heat, by forming with copper an alloy called white tom- bac ; we may remark, that this alloy, which may be also formed by fusing together in a close crucible copper and arsenic, (covering the crucible with com- mon salt to prevent the action of air,) is white and brittle, and when the quantity of arsenic is small, it is both ductile and malleable. The quantity of copper, and also of arsenic, may be learned by dis- solving the tombac in nitric acid, previously weigh- ing it, and separating the copper in its metallic state by a plate of iron ; the loss sustained will indicate the proportion of arsenic. The arsenic will be acid- ified by the nitric acid, and remain in the solution. If this be saturated with soda, the liquor filtered, and nitrate of lead added gradually, an arseniate of lead will be precipitated, 100 parts of which are equiva- lent to 56.5 of metallic arsenic. Another process may be adopted, similar to that described by Mr. Chenevix, for examining the native arseniate of cop- per; namely, digest the alloy in nitric acid, and add nitrate of lead, which will form an arseniate'of lead ; but if there should be an excess of acid, part ofthe arseniate will be held in solution ; in that case, evap- orate the fluid nearly to dryness, and add alcohol. ( 255 ) rthich will separate the whole ofthe arseniate of lead : to the remaining solution add potash, and oxyde of copper will be precipitated, 125 parts of which are equivalent to 100 of copper. SEALING WAX. There are two kinds of sealing wax; the red and the black. They both contain resin of a particular kind, and coloured with red lead, vermillion, or ivory black. A variety of recipes have been published for preparing them. Good red sealing wax, or that which is denominated superfine, should have a fine vermillion colour, and when broken a glossy and resinous fracture. It should inflame without diffi- culty, and exhale an aromatic odour resembling the mixed odour of burnt camphor and benzoin. It ought to dissolve in alcohol, leaving nothing but the colouring ingredient. This should be vermillion for the red, and ivory black for the black wax. The common sealing wax is usually made by melting re- sin and shell lac, and colouring it with red lead or ivo- ry black. The superfine red wax is formed of resin shell lac, and camuhor, with occasionally benzoic ac- id, and coloured with vermillion. Very inferior sealing wax has been sold for superfine, or No. 1, by ■carnishing.it with a spirit varnish made by dissolv- ing the best red sealing wax in alcohol. In this way, even a mixture of common rosin and yellow wax, coloured with red lead, has been passed off for the genuine sealing wax. But the fraud is readily detected by breaking it, and burning a small ( 256 ) piece, observing the flame, smoke, &c. The colour which is communicated by vermillion, and by red lead, is readily recognised; the former is a bright red, and the latter a dull red. We may examine it, by first dissolving all resinous substances by means of alcohol, and proceeding with the residue in the usual way for the detection of lead or mercury. If the colouring matter be red lead, a piece of the wax put into a crucible and submitted to heat will be decom- posed, and the lead reduced.* COPAL. This substance, usually called gum copal, is em- ployed in the manufacture of the celebrated copal varnish. It is obtained from the thus copallinum. No less than eight species have been enumerated by Hernandez. As upon the purity of copal depends, * There is one fact, which, perhaps, is worthy of remark.— When sealing wax is melted in the flame ofa candle,it is more or less contaminated with lamp black, which arises not from the wax itself, but from the combustion ofthe tallow. To prevent this effect, if it be melted in the flame of a spirit of wine lamp, no carbon will be deposited. The wax will not be in the least co- loured. This difference arises from the combustion of the two ' substances: in the combustion of tallow, water as well as lamp- black is produced ; but, in the combustion of alcohol, no smoke is to be observed, as the products of combustion are water and carbonic acid, and consequently all the carbon is consumed.— We may also remark, that in the burning of oil in the Argand lamp, with a glass cylinder, the combustion is perfect; for the smoke (lamp black,) is wholly consumed by the current of at- mospheric air formed by the cylinder, and hence the result is al- so carbonic acid and water: the carbon itself is consumed in the cylinder, in consequence of the free supply of oxygen. ( 257 ) in a great measure, the quality of the varnish, so it is of importance to determine its genuine character. Copal is a white resinous substance, with a tinge of brown. It is sometimes opaque, and sometimes it is almost perfectly transparent. It differs from other resins in several particulars. Although it dis- solves in alkalies, and in nitric acid with the usual phenomena, and agrees in this respect with the other res ns, yet it is not soluble in alcohol, nor in oil of tur- pentine except by peculiar management. It resem- bles gum anime in appearance, but is easily distin- guished by the solubility of this last in alcohol, and by its being brittle between the teeth, whereas anime softens in the mouth. The specific gravity of copal varies from 1.045 to 1.139. Copal varnish is merely a solution of copal in a volatile menstruum. The goodness of this varnish is determined by its transparency, and freedom from colour. This solution is usually effected by melting the copal in a moderate heat, and mixing with it an equal quantity of linseed oil, which has been bleach- ed. Oil of turpentine is also added with the linseed oil. In fact the best copal varnish is said to be formed by dissolving the copal in old oil of turpentine. Cam- phor, oil of rosemary, he. have produced good co- pal varnish, when used with other substances as sol- vents of the resin.* *We may remark here, that varnishes are numerous; ihat rliey are all formed by the solution of resin in alcohol, or dry- ing oil or essential oil, and hence are denominated spirit and oil vanishes Lacquers, which are a kind of varnish,, are gre=- 22* ( 258 J LAC, This substance is used extensively in varnishes, in sealing wax, and in lacquers. It is deposited on dif- pared usually by dissolving sundry substances in alcohol. Thus the lacquer for tin ware is formed by macerating shell lac and turmeric root in alcohol. Amber varnish is formed by dissolv- ing amber in drying oil, and adding spirit of turpentine ; mastic varnish, for fire screens, window blinds, transparencies, &c. is a solution of mastic in spirit of turpentine; gum elastic varnish, for aerostatic machines, is a preparation of that substance with oil of turpentine, or aether ; and shell lac, gum elemi, common rosin, &.c. have all been used for the preparation of spirit var- nish. The coloured resins, as gamboge, dragon's blood, &c. are used in coloured varnishes. The best gold varnish, or gold lacquer, is made by dissolving 2 oz. of shell lac in 2 oz. of alcohol, and adding 1 oz. each, of anatto and turmeric, and 30 grs. of dragon's blood. Varnish^ t when applied to a body, should be put on with care, and when dry, should be smooth, shining', and uniform. No granulations should appear; if so, we may inter the impurity of the resin employed in its fabrication. Coach bodies require the best co- pal varnish ; the body is first -painted before it is applied. This varnish is extremely beautiful, and should resist the action, as in fact all resinous varnishes, ofthe weather. As the solvent of resins is either sundry drying oils or alcohol, it is obvious that, as water has no action on resin, it can have none on varnish. To remove varnish, it is, therefore, necessary to employ alcohol and oils. A solution of gum-resin, when used as varnish, it af- fected in a degree by water, owing to its solvent power on the gum. Coarse varnishes are chiefly used for wood work, as turpentine varnish, in which the oil or spirit of turpentine is us- ed as the solvent; but spirit varnish, as it communicates no stain, is generally used for paper, as for maps, globes, &,c. Even dry- ing oil, or boiled linseed oil, when ground with pigments, pre- vents the action of the weather on the same principle as var- nish. < 259 ) ferent species of trees, by an insect called chremes- lacca. There are various kinds of lac distinguished in commerce, as the stick lac which incrusts small twigs; the seed lac, which is the preceding boiled in water; and shell lac made by melting the seed lac, and reducing it to the state of thin crust. Stick lac yields to water a substance which is used as red dye.. Water should dissolve the greater part ofthe colour- ing matter of lac, which varies from 15 to 1-2 per cent, but alcohol should dissolve the greater part of the resin, the chief ingredient in the composition of lac. In sulphuric acid, it becomes partly charred; but in nitric acid, it should dissolve, and the acid should produce the same changes on it as on other resinous bodies. Muriatic and acetic acids also act as solvents. The fixed alkalies readily dissolve lac. The colouring matter possesses the properties of ex- tractive. The quantity of resin amounts from 08 per cent, in stick lac to 90 per cent in shell lac. A solution of borax in water readily dissolves lac, and this solution has been applied to important pur- poses. The best proportions are 20 grains of borax, 4 ounces of water, and 11 grains of lac. We men- tioned when speaking of black pigments, that Indian ink was a combination of lamp black and gum or ge- latin ; but an author assures us, that the true Indian ink is a mixture of this solution of lac in borax, with lamp black, and that the same solution may be em- ployed for many ofthe purposes of varnish. A very useful cement, which will resist moisture, is made by dissolving shell lac in alcohol, and mix- ( 260 ) mg it with a solution of isinglass in proof spirit. Tins cement if made very thick, and applied to pieces oi china or broken glass to be mended, or joined togeth- er, and the ware then exposed to the rays ofthe fire,— the union will be so perfect, and at the same lime so strong, that it is difficult to separate it. The mastic of jewellers is a cement composed principally of lac ; but gum mastic is frequently used alone, the stone being previously made hot enough to melt it. The Armenian jewellers in Turkey, ornament watch cases with gems by glueing them on with similar cement. A new cement has lately been imposed on the public. some of which I purchased in Philadelphia, for the purpose of joining broken ware; on examination I found it to be nothing more than shell lac cast into sticks. It is, however, an excellent cement. The pieces should be healed, and the lac melted on ; then joined together as quickly as possible. The temperature required is about that of boiling water. Lac is chiefly used in spirit varnish ; the varnish however, is always coloured. AMBER Amber is undoubtedly of vegetable origin. It gen- erally agrees with resins in its properties. It is brit- tle, light, and hard, sometimes transparent, but com- monly yellow. When heated it softens, and loses some of its weight. In a strong heat it burns, leav- ing a quantity ef ashes. Water has no action on it; but alcohol by long digestion, dissolves about 1.3d o* I 201 ) the amber, which becomes milky when mixed with water. This precipitate possesses the properties of resin. Boiling fixed alkali dissolves it, and the compound has the characters of soap ; for it is soluble in alco- hol, and not thrown down by water. Sulphuric acid converts it into a black resinous mass, and nitric acid acts upon it, producing a copious disengage- ment of nitrous gas. When amber is distilled, it fur- nishes gaseous matter, an acidulous fluid, then an oil, and lastly an acid, the succinic. Amber be- comes electric by friction. It was the electrum of the ancients. Neither fixed nor volatile oils have any action on amber, unless it has been previously roasted, or exposed to a melting heat. When thus heated, it combines with oils, and the solution forms amber varnish. Good amber should be in large pie- ces, ofa yellow or amber colour, and, when submit- ted to experiment, should exhibit the characters we have mentioned. Amber is used in the preparation of varnish ; but as neither fixed nor volatile oils have any action up- on it, unless it has been previously roasted or expo- posed to the melting heat, it is necessary, in order to effect its solution, to be treated in that manner.— When amber is roasted, it loses about one half its weight; and when mixed with three parts of dryed linseed oil, and the mixture exposed to the action of a gentle heat, the amber will be dissolved. After being removed from the fire, and when nearly cold, four parts of oil of turpentine are to be added. This forms the amber varnish. ( 262 ) ROSIN. This substance although common, presents se- veral varieties as to quality. What is denominated turpentine, which is obtained from different species of the^r, as the pinus abies, sylvestris, larix, balsam- ea, he. has received different names. Thus, the pi- nus abies yields frankincense, which burns with a fragrant odour; the p. sylvesitris, the common tur- pentine; the p. larix, the Venice turpentine ; and the p. balsamea, the balsam of Canada. Some of these turpentines may be mixed with an undue proportion of spirit of turpentine; but the admixture may be de- tected by comparing it with the genuine. Fluid turpentine, as it exudes from the tree, is composed of oil of turpentine and rosin ; and, there- fore, when it is distilled, the oil comes over, and the rosin remains behind. This residue is the common rosin, or colophonium. When, however, as in the distillation of spirit of turpentine, a quantity of wa- ter is put into the still along with the turpentine, the rosin then becomes yellow, and forms the yellow ro- sin of the shops. The yellow rosin when heated should not give out any oil. It should be brittle, and pulverise easily, be insoluble in water, but soluble in ajcohol and spirit of turpentine. WThen exposed to the action of the sun and moisture, its colour, is grad- ually discharged, and finally becomes white, form- ing white rosin. Rosin forms the basis of coarse turpentine varnish. Pitch differs from rosin inas- much as it it is nothing more than inspissated tar. ( M* ) BALSAM. OR BALM OF GILEAD. The balm of Gilead is a resinous juice obtained from an evergreen tree, or shrub, of Arabia. The finest is of a greenish colour called opobalsam. The second is the carpobalsam expressed from the fruit. The third variety is reddish, called xy labalsamum, pre- pared from a decoction ofthe branches. The plant was supposed to be the amyris Gileadensis and opobal- sam Lin. Wildenow, vol. ii. p. 334. The first sort which naturally exudes from the plant is scarcely known in this country. It is tur- bid and whitish, of a strong pungent smell like that of turpentine, but much sweeter and more fragrant, of a bitter acrid astringent taste. On being kept it becomes thin, limpid, light, greenish, and of a golden yellow ; after whicli it is thick like turpentine, and loses much of its fragrance. Having the smell of citron, or ofa mixture of rosemary and sage flow- ers, its imitation has been attempted by mixing with oil of turpentine, some of the oils of rosemary and sage, and adding a due proportion of this mixture to the Canadian balsam. It is never so perfect, but the fraud may be detected by merely comparing it with the genuine. The Canadian balm of Gilead-fir affords a balsam that is often imposed as the genuine sort. If the true balsam is dropped in water when thin, it spreads itself on the surface, imparting to the water much of its taste and smell. The grosser part which remains at the top, is thick enough to be tak- ( 264 ) en up with a needle : this is reckoned a mark of its being genuine. If pure balsam is dropped on a woollen cloth, it may be washed off without leaving a stain, but the adulterated kind adheres to the place. The pure coagulates with milk, but the adulterated will not. CANADA BALSAM. This is a turpentine which exudes from the pin us balsamea and Canadensis, has a grateful odour, is more or less white, and when pure, thick and visced. It is frequently thinned by oil of turpentine. Pure Canada balsam will not flow without it be heated. BALSAM OF COPAIBA. This is obtained from the copaifera officinalis. It is at first colourless, but becomes yellow by time, without losing its transparency. The smell is frag- rant ; the taste aromatic, bitter, and somewhat sharp, and permanent on the tongue. By distillation in water we separate the oil from the resin ; and, in the former, the taste and smell of the balsam are concentrated. About half of the bal- sam rises, and is condensed in the receiver, in the form of oil. Balsam Capaibae unites with fixed and volatile oils, and with alcohol. It is frequently adulterated with spirit of turpen- tine. The fraud is not easy of detection, as the bal- ( 265 ) /dm itself contains this oil; but the mixed balsam i« thin, has more of the turpentine smell, and appears to envelope the peculiar smell of the pure balsam. VVrhen compared, therefore, with the genuine, the difference may be detected. The turpentine can scarcely be disguised if a little of the suspected bal- sam be rubbed in the palm of the hand. The tur- pentine is also thicker, and less yellow than the co- baiba?. Another mode of adulteration is to distil a portion ofthe oil of copaiba?, with cheaper essential oils. This fraud can scarcely be detected. The balsam is weaker, and may be compared with the iienuine. It will require a longer time, and more alcohol, for its solution than the pure. PERUVIAN BALSAM. This is obtained from Peru, and procured from a tree, the myroxylon peruiferum. The native balsam which naturally exudes is white; but this we never meet with. The inspi-sated balsam forms the white storax. This, however, is usually of a reddish col- our. What is usually sold is the black or dark red balsam, which is a decoction of the branches inspis- sated. It does not mix with water, but imparts to ' it an aromatic smell. It is soluble in alcohol, but fixed oils take up the essential oil, and leave the resin.—* Baume speaks of one adulteration of this balsam; namely, with the second oil which rises from benzoin digested on poplar buds. By attention to its solu- bility in alcohol, and decomposition by fixed oils, the genuine balsam may be known from the spurious. op, ( 266 ) BALSAM OF MECCA. This is said to be the same as the balm of Gilead. The plant or tree which furnishes this balsam grows between Medina and Mecca, and according to Al- pinus is brought to the green houses in the neighbor- hood of Cairo. This balsam, as well as the plant, which furnishes it is held sacred like the mistletoe of the Druids, which should only be cut with a golden sickle. Some branches yield only three or four drops in a day, and the most fertile ones only from thirty to sixty drops. The branches are burnt in the temples. This balsam consists of a very fragrant etherial oil combined with resin; the former may be separa- ted from the latter by distillation. It is dissolved in alcohol only by heat, and the addition of water causes a milkiness, and a separation of the oil and resin. It unites with volatile oils. According to Hasselquist (Travels,) it is adultera- ted with the Cyprian turpentine, the oil of sesamum, the fat of the ostrich, he. The fine turpentine, which exudes from the ruptured vesicles of the pinus balsamea, is often substituted for this balsam. Al- though the Mecca balsam, and the balm of Gilead have been greatly extolled by the ancient physicians. who believed they possessed the powers of that empirical nostrum, the elixir vitae, which was sup- posed to give new life to embodied man, yet Quarin in his Animadversiones Practicae has informed us, that even the best of the Mecca balsam is scarcely, if at all, superior to boiled turpentine ! ( 267 ) SOAP. Soap, a combination of fatty matter with caustic soda or potash, is frequently found adulterated.*— Soap should be completely soluble in soft water, without leaving a residue. In London it is the prac- tice to adulterate white soap with a very fine white clay, brought from St. Stephens, in Cornwall; a fraud which is easily detected by dissolving the soap in water, and observing the insoluble part. Brown soap, which is the white hard soap colour- * Without noticing the effect of elain and stearin, or of oleic and margaric acid, produced in saponification, in the constitu- tion of soap, we may remark, that soaps are combinations of oil or fat with particular basis. Thus we have soft soap, made by fatty matter with caustic lie sufficiently strong to bear an egg ; hard soap, by combining fat or oil with caustic soda; earthy soaps by adding earthy salts to a solution of soap in water, which are insoluble; and metallic soaps, by adding metallic salts to soap in the same manner. When caustic potash is us- ed, t!ie soap is soft; but when custic soda, it is hard: if, howe- ver, we add to the soft soap a due quantity of muriate of soda^ it will be converted into hard soap, or soap of soda, a process used by our soap boilers. The muriatic acid unites with the potash of the soft soap, and forms muriate of potash, which remains in solution, and constitutes the icaste lie ; at the same time the soda, of the common salt, combines with the oil or fat and forms a new compound, which becomes hard, and is the same which is formed by the direct union of oil or fat with caus- tic soda. If kelp, barilla, or natron, which contain the same alkali, (so- da,) can be had cheap, there is more economy, and certainly more expedition in using it; as in Europe, up the Mediterra- nean, kc. it is chiefly employed. In the preparation of hard •»oap, from the soda of commerce, which is pounded and mixe.ri ( 268 ) ioured by rosin, may be adulterated in like mannei with brown ochre, or other foreign substance. Soft soap or soap 6f potash is a semi-fluid soap, prepared by boiling sundry fatty substances in caus- tic lie. When the saturation of the lie with fat is effected, the compound acquires a certain degree of consistency, and the true soft soap is formed, which is then mixed with a variable quantity of water.— This addition is by no means adventitious. In order to make the soap bear a larger quantity of water, it is frequently combined with hard soap; or, in fact, rosin alone is often added in the boiling ofthe soft soap. Rosin, however, makes soap more detergent. Any foreign ingredient in soap, such as earthy |ii a wooden vessel with about a fifth part of its weight of lime, the liviuiums are made of different strengths: thus, the specific gravity of the first lie should be about 1.200. The quantity of oil made use of is about six times the weight ofthe soda. Olive oil makes the best soap ; next to which is tallow. A great va- riety of oils may be employed. Whale oil has been long in use by the Dutch for the manufacture of soft soap. Hard soap va- ries very much in its proportion of water ; fifty per cent, has even been detected, and thus tbe purchaser pays half of his money for water! On the supposition that soap is a combination of the oleic and inargaric acids, and admitting no adulteration, the composition af hard soap is stated as follows: 1 atom margaritic and oleic acids,.....64.49 1 atom soda, -------.-... 7,57 28 atoms water, --------.__ 27.94 100.00 ( 269 ) matter, may be known by dissolving it in water.'— Pure white soap should be wholly soluble in alco- hol, and should consist of nothing more than talloW and soda. Alcohol digested on brown soap, as it is formed of a given quantity of rosin with the tallow and alkali, (which combination is soluble in alcohol,) should take up the whole ofthe soap. In hard soap the whole of the superfluous lie is totally extracted before finishing; but in soft soap, all the lie used is retained. It is supposed, as we remarked in a pre- ceding note, in consequence of the combination of oleic and margaratic acids with bases, especially the former, in producing analagous compounds, and the existence of stearin and elain in fixed oils and tal- low, which become changed into these two acids in the process of saponification, that soaps are nothing more than the combination of these acids with salafi- able basis. Very fine white soap is made of olive oil and soda. When this soap is impregnated with sundry essen- tial oils, it constitutes the perfumed soaps. Windsor soap should be nothing more than pure white soap, ofthe first quality, scented with the oil of caraway seed. It is frequently adulterated with starch to give it a better appearance, and feel softer to the skin. This admixture may be detected by dissolving the soap in alcohol. It is well known, that in consequence of the pres- ence of earthy salts in sea water, soap cannot be us- ed for washing with that water. In this respect sea water resembles the action of hard water, but in a 23* / ( 270 ) greater degree : See page 7. This effect may be prevented, in a considerable degree, by adding previously some potash, or soda, which will decom- pose the earthy salts, and thus prevent their action on soap. Advantage is taken of this fact by sea- men ; but the Chinese, although possessing no chem- ical science, in the true acceptation of the term, know the effect ol sea water on soap, and are acquainted with the circumstance of its decomposition by salt wa- ter, and the use of alkali in preventing it. They, therefore, prepare a soap expressly for washing in sea water, some of which we have seen, and exa- mined ; it merely consists of an extra quantity of al- kali, more than is actually required in forming the soap, so that while the extra portion decomposes the earthy salts, ihe soap itself suffers no change. Soap has been used for other purposes besides washing, or rather soap ofa particular make. Pliny informs us that the German soap, with which the Germans coloured their heads red, was imported to Rome for the use of the fashionable Roman ladies. Beckman observes " there is no doubt that the pila mattiaca, which Martial recommends as a preven- tive of gray hair; the eaustica spuma, with which the German's dyed their hair; and the Batavian froth or lather, which the Romans employed for colouring theirs, were German soap. It is probable that the Germans tinged it with those plants which were sent to Rome for dying hair; and according to the modern manner of speaking* it was more properly a kind of pomade than soap." V ^1 ) Before the invention of soap for washing, the an- cients used the gall of animals, the sap of many plants, and plants of a saponaceous nature. Clothes were frequently oleaned by being rubbed and stamp- ed upon in water, without the addition of any sub- stance. Homer remarks, that Nausicaae and her at- tendants washed their clothes in this manner in pits. At later periods ashes and a lie of ashes were era- ployed for washing; and although ihe method of strengthening lie (depriving the alkali of carbonic acid,) by means of unslacked lime was known in the time of Paulus iEgineta, yet the Romans were un- acquainted with potash, or the art of making it. But an alkali, which nature presents in abundance in some parts ofthe world, we mean soda, or min- eral alkali, was long known and used in washing.— This was the nitrum ofthe ancients, or as the peo- ple of Attica pronounced it, litrum. The lake As- canius, mentioned by Aristotle and Pliny, in conse- quence of containing an alkaline liquor, was used by scourers for washing clothes ; a fact also mentioned by Strabo of a water in Armenia. The same alkali occurs in Scripture under the name of borith, and was used for washing by the Hebrews. The ancients made ointments of soda and oil, but not soap, whicli appears rather remarkable. In short, many substances were used for washing; even stale urine was collected for the purpose. Fuller's earth was also employed, of which nature was the cretce fullonia of Pliny, and other earths, as the terra dm- olia, &c. used for scouring and washing. ( 272 ) The action of soap in removing grease, dirt, fee's well known; "but if the object be to separate grease alone, as in the scouring of wool, woolen cloth, he. it is not an uncommon practice to use potash, which combines with the oil or grease into a soap, and thus the grease is readily removed by water. A soap for the removal of grease spots or stains from linen, cam- brics, he. has been sold in small cakes ; it is nothing more than the soap of soda containing a little excess of soda. The liquid shaving sOap, a.few drops of which will form a lather with water, is merely a solution of soap in alcohol. A liquid green and black soap is made in Picardy and Holland, by boiling the lixivium of soda, potash, or wood ashes, with the marc of the oil of olives, of nuts, or of mape ; or with fat, or fish oil, he. Mar- bled, or variegated soap, such for instance as wash- balls, is prepared by adding sundry substances in due proportions, as a solution of sulphate of copper, and sulphate of iron, which are decomposed by the alka- li, and the oxydes of copper and iron are precipitat- ed; which give a marbled appearance. Vermillion, infusion of cochineal, he. are also used to commu- nicate colour. POTASH, PEARL ASH AND BARILLA. The adulteration of potash, pearl ash and barilla, articles of importance to the bleacher, dyer, glass- maker, andsoap boiler, is carried toa great extent, and ( 273 ) tew objects of commerce are found more, frequently sophisticated. Potash and soda are compound bodies, having a metallic basis, called respectively potassium and so- dium, united with oxygen; they are, therefore, me- tallic oxydes. When wood is burnt to ashes, the ashes lixivated with water, and the solution filtered, and evaporated to dryness potash will be obtained. It is not, however, in a state of purity ; but when heated to redness in a reverberatory furnace, many of its impurities are burnt off; it becomes much whit- er, assumes some degree of lustre, and is then the pearl ash of commerce. It still contains foreign mat- ter, as some salts, and a large proportion of carbonic acid, from which it is separated when used by the soap boiler by means of quicklime. It is then caustic pot- ash, and in its solid state is often used by surgeons under the name of potential cautery. When potash is submitted to the action of a galvanic battery, plac- ed upon a disc of platinum attached to the negative end of the battery, and a wire from the positive ex- tremity is made to touch the upper surface, globules of potassium will appear at the side in contact with the platinum disc, and oxygen gasvvillbe libera- ted at the extremity ofthe positive wire. This dis- covery was made by Sir H. Davy in 1807. Gay Lussac and Thenard have since discovered, that potassium may be obtained, and in greater quantities? by passing potash through iron turnings heated to whiteness in a gun barrel. It will be sufficient at ibis time to add, that according to the result of differ- ( 274 ) ent experiments, potash is a compound of 100 pot- assium and 20 of oxygen, and that another compound containing more oxygen has been discovered, which is called the per oxyde of potassium. Another com- pound, containing less oxygen than potash, has also been pointed out. Soda or the fossil or mineral alkali is found native in combination with carbonic acid, in different parts ofthe earth, particularly in Egypt; and is found a- bundantly in combination with muriatic acid, in the state of rock salt, sea salt, sal gem, &c. Various marine plants, especially different species of the sal- sola particularly the salsola soda, when burnt, and the ashes lixivated, usually furnish the soda of com- merce. A plant called barilla in Spain, also pro- duces it; hence it is likewise named barilla. The algae, especially the fuci, furnish some quantities of soda. The ashes of these plants are known by the name of kelp ; in France they are called varec. So- da has been obtained in considerable quantity from common salt, and Glauber's salt. Soda may be de- composed in the manner already mentioned form pot- ash, and the basis obtained in a separate state. It is composed of 100 sodium, and 33.3 of oxygen. In one respect both sodium and potassium agree ; viz. when they are brought respectively in contact with water they decompose it, and are changed into soda and potash; and when heated in oxygen gas, they burn with great splendour, and unite with a maxi- mum of oxygen, forming the per oxydes of sodium and potassium. Sodium also, like potassium, when ( 275 ) exposed to the air, is speedily converted on its sur- face into soda. In short, its affinity for oxygen is sim- ilar to that of potassium. The soda of commerce, we may remark, is very impure: it contains carbonic acid, common salt, and other foreign substances; it may be purified in the same manner as potash. Potash or soda, obtained by means of alcohol, is a combination of potash or soda and water, or a hy- drate of the alkali. These alkalies, it is known, are obtained in a pure state by depriving them of carbon- ic acid, and dissolving the dry caustic alkali in al- cohol, and driving off the alcohol by heat. Pure potash was obtained by Sir II. Davy by exposing per oxyde of potassium to heat; and pure soda, by burn- ing sodium in a quantity of air just sufficient to con- vert it into soda. As potash, pearlash and barilla are only valuable 10 the manufacturer in proportion to the real alkali they contain, this fact may be learnt by the quantity of acid they will saturate, which must depend on the quantity of free or absolute alkali. An instrument was invented for this purpose called an alkilimeter, founded on the principle above stated. The first instrument of the kind was that of M. Descroizilles, and the acid made use of was the diluted sulphuric. The method recommended by Mr. Kirvvan, and described in the Transactions of the Royal Irish Ac- ademy for 1789, was predicated on the quantity of alum decomposed by the alkali under examination. The principle is the same. The olilv merit that De?- ( 276 ; croizilles or Dr. Ure can claim, is improving on the principle and method of Mr. Kirwan; but Dr. Ure has certainly very greatly improved the alkilimeter, and made it a general and useful instrument—the conclusion by which, instead of being arbitrary as in the French instrument, is now uniform and sat- isfactory. You will find the instrument described, and the mode of using it, in Henry, vol. ii. p. 38L to which I refer you.* *Asthealkalimeter is of great utility, it may not be impro- per, nevertheless, to notice briefly its construction and applica- tion. A tube nine inches and a half long, and three fourths of an inch internal diameter, having a lip, and holding 1000 grains of water, or alittle more, is accurately graduated into 100 equal parts, which are subdivided in ten parts each, but the latter are sometimes dispensed with. These graduations are made by pouring in successive portions of water of 100 grains each.— The 1000 grainsis marked 0 ; the tenth below this 10 and soon. The test acid is made by diluting one part of sulphuric acid of commerce of sp. gr. 1.849 with four parts of water. It is neces- sary to be provided with Dr. Wallaston's scale of equivalents ; for, when an alkali is to be examined, we must find how many trains of sulphuric acid are required to neutralize 100 grains of the alkaline ingredient. For example pearl ash : we find 100 trrains of subcarbonate of potash are equivalent to 71 grains of concentrated sulphuric acid, and 355 grains of the diluted acid, equivalent thereto, are put into the tube. Then fill the tube to 0 with water. Now the 100 measures contain a quantity of a- cid equivalent to 100 grains, of subcarbonate of potash; each measure, therefore, in the tube is sufficient for the neutraliza- tion of one grain of the subcarbonate. Dissolve 200 grains of the potash in 2 oz. measures of distilled water, and filter the so- lution and wash the filter with 2 oz. more of water, and mix the two together. Divide the solution in two equal parts. To one portion addthe diluted acid very gradually, so as to attain the ( ^ ) If a given quantity of alkali be dissolved in water, and saturated with nitric acid, the presence of sul- phuric and muriatic acid may be shown by using respectively nitrate of barytes and nitrate of silver. As the earthy and metallic sulphates and muriates are incompatible with uncombined alkali, i. e. they cannot exist together in the same solution, we need not apprehend the presence of salts of that descrip- tion.* The alkalies, however, are combined with more or less carbonic acid ; the amount of which * We speak of the solution of the alkali. If these salts are mixed with dry alkali, no change will take place ; but if the al- kali should contain them as adulterations, the moment it is dis- solved in water, decomposition will ensue. point of neutralization, which is known by the liquor having no effect on litmus paper and turmeric paper. Tiie number on the test tube, at the level of the acid remaining in it, shows at once, without calculation, the quantity per cent, of subcarbonate of potasli contained in the pearl ash, which is usually 80 per rent. The process is the same for barilla, kelp, or any variety ofthe mineral alkali, except 93 of sulphuric acid are equivalent to 100 of subcarbonate of soda; and, according to Henry, we must take 93.5—465 grains, of sulphuric acid of density l.1 41. We may mark on the tube, to spare trouble on any future occasion, it 355 grains Equiv. of Subc. Pol.; at 465 Enuiv. of Subc. of Soda ; at 520 Equiv. pure Pot. and at 783 grains Equiv. pure Sod'i. With regard to the further use of Wailastoirs scale—for example with subcarbonate of potash in any sample of potash, it is to find its equivalent quantity of pure or caustic potash.-*- Thus, if the pearl ash contains 80 per cent, of subcarbonate, bring that number to subcarbonate of potash on the scale, and its equivalent in pure potash will be seen to be 85. The same in- strument may be used to determine the strength of any acid whose equivalent is known, by reversing the foregoing proce« It becomes then an acidiineter. 24 ( 278 ) may be ascertained by noting the loss sustained after ^he. effervescence ceases on the addition of acid, de- ducting from that loss the weight of acid made use of. But the principal point is to know the quantity of absolute alkali in the alkalies of commerce ; and this, we remarked, depends on the quantity of alkali required to saturate a given portion of acid, and is more generally performed by the alkilimeter. MANGANESE. This is another substance, frequently impure, or adulterated. It is important to the bleacher and glass maker; to the former, in preparing his bleach- ing liquor, and to the latter in rendering glass colour- less. The best manganese is of a velvet black colour, and when exposed to the action of heat, should fur- nish an abundance of pure oxygen gas. Oxyde of manganese,, before the blow pipe, gives with microcosmic salt in the exterior flame a fine amethyst colour, which disappears in the interior flame. With borax it gives a yellow hyacinth red glass. If, in consequence ofthe presence of iron, it does not give the requisite colour, the addition ol nitre will form a glass ofa dark violet while hot, and reddish violet when cold. Chalk appears to be the principal admixture with manganese, which occurs with it in nature, and more frequently fraudulently added. The injurious effect of the presence of carbonate of lime, must be obvl- f 279 ) rms when wt consider the formation of chlorine bv the admixture of muriate of soda, oxyde of manga- nese and diluted sulphuric acid; viz. that besides chlorine, we would have carbonic acid gas. The detection of carbonate of lime is effected by first pouring nitric acid, diluted with eight or ten times its weight of water, on ihe suspected manga- nese. If an effervescence ensue, and the acid is af- terwards affected by oxalate of ammonia, carbonate of lime is proved ; the quantity of which may be known by adding to the solution carbonate of potash; and collecting, washing, and drying the precipitate, and then weighing it. Some ofthe ores of iron may be found with manga- nese; and, in short, the two metals,may occur, as they frequently do, in the poorer brown paemetetic and bog iron ores. The separation of the metals from each other, so as to ascertain the proportion of each, may be effected, according to Klaproth, by means of nitric acid with the addition'of sugar, which will on- ly act upon the manganese. There are several processes that have been used for the same purpose. Thus, if the iron be in such a state of oxydizement as to be soluble in muriatic acid, a portion may be accordingly dissolved; and, after diluting the solution largely, adding a solution of crystallized carbonate of potash, (bicarbonate,)which will precipitate the iron in the state ofa coloured oxyde, or rather carbonate, while the manganese in consequence ofthe excess of carbonic acid, will re- main suspended- ( 280 ) When the gray radiated ore of manganese, in fine powder, is digested in muriatic acid, it is entirely dis- solved, with the exception of about 3 to 4 per cent. of silica. The solution, containing manganese and a portion of iron, when mixed with ammonia will be decomposed ; an oxyde of iron will be precipitated, and the manganese remain in solution. The oxyde of iron, if ignited with a little wax, will be reduced to the state of protoxyde. If the solution be evap- orated to dryness, and the mass moistened with ni- tric acid, and then exposed to heat, the per oxyde of manganese will be obtained. By this process the real quantity ofthe per oxyde of manganese in a spe- cimen of the ore may be ascertained. Chlorine gas should be abundantly formed by the affusion of muriatic acid on oxyde of manganese ; by which hydro-chloric (muriatic) acid is deprived of its hydrogen by the oxygen of the oxyde, water and chlorine being produced. The black wadd of Derbyshire, is an ore of man- ganese, but very remarkable for its spontaneous com- bustion with oils. SULPHUR. Brimstone, which comes to us in rolls, contains a variety of foreign substances, some added intention- ally. Sometimes flour, gypsum, he. are mixed with it, previously to its being formed into rolls, or sticks. The purest kind is the flour of sulphur, which is mad,e from the common kind by sublimation. Mas- ( 281 ) sive sulphur is chiefly brought from Sicily. It oc- curs native, and is found associated with sulphate of lime, sulphate of strontian, and carbonate of lime. The crude sulphur is chiefly obtained from certain me- tallic sulphurets, as sulphuret of copper, by roasting them, and collecting the sulphur in a proper cham- ber, where it is gradually deposited; it is then melt- ed, and cast into sticks or rolls. In the preparation of gun powder, it is necessary that the sulphur should be pure. Any foreign sub- stance, it is obvious, will injure the effective force of the powder, which we shall notice hereafter. In France, two methods are used for purifying sulphur for gun powder: the first consists in melting it in £ large kettle, and suffering it to remain in a fluid state with a gentle heat, by which the greater part of the impurities, being heavier than the sulphur, gradual- ly settle; the extraneous matter, which may float on the surface, is removed, and the fluid part separated without disturbing the sediment. This, however, at best is but an imperfect purification. But the se- cond method consists in sublimation, and, therefore, is preferable. The vapour of the sulphur is receiv- ed in large chambers, where it condenses. The re- sidue, after sublimation, is sulpur vivum, compos- ed of a portion of sulphur combined with the impuri- ties, as the earths, &/\ The purity of sulphur may be ascertained by heating it gradually upon a piece of platinum leaf, or by distillation in a glass retort; if any thing remain iixedj it is an impurity; the quantity of which in th* 24* { 282 ) sulphur may be learnt by weighing it before, and weighing the residue after the experiment. It should be perfectly soluble in boiling oil of turpentine. Potash will act upon, and dissolve sulphur; hence sulphur should be totally dissolved by boiling it with a solution of pure potash. Any residue indicates fo- reign matter; the nature of which, if necessary, may „be learnt by experiment. Impure sulphur, when consumed by burning, leaves generally a residue of oxyde of iron, and sil- ica. The mode of ascertaining, with great accuracy, the proportion of sulphur in some compounds, as in gun powder, is by using chlorine. In gun powder, for instance, we first separate, and ascertain the quan- tity of nitre; then subject the residue, consisting of charcoal and sulphur, to the action of chlorine gas ; and the chloride of sulphur, thus formed, is volatili- zed by heat, leaving the charcoal. If any foreign substance be suspected in the flow- er of sulphur, it maybe proved by the reagents al- ready mentioned ; but there is one substance usual- ly met with in sublimed sulphur, viz. sulphureous acid. It may be recognised by the acid taste of the sulphur, and its effect on vegetable colours. Wash- ed flower of sulphur should never contain it. MILK OF SULPHUR. The milk of sulphur and the precipitated sulphur ofthe pharmacopeas, is liable to contain foreign sub- stances. f 283 ) It is prepared by precipitating the sulphur from the sulphuret of potash, or other alkaline sulphuret, by an acid, in consequence of which a compound of acid and alkali is found, which should be thorough- ly washed off. If the acid employed as the precipi- tant is the muriatic, its presence may be known by washing the milk of sulphur in water, and adding to the washings, after filtration, nitrate of silver. Milk of sulphur is a hydrate of sulphur, or a com- bination of sulphur and water. If exposed to heat, it will be deprived of its whiteness, and water will be given out; the sulphur will then assume its original colour. Water dropped into melted sulphur, will give that portion with which it comes in contact, the white colour ofthe milk of sulphur; and sulphur sublimed in a vessel containing the vapour of water, will be converted into the same substance. The whiteness of sulphur, therefore, indicates -the presence of water; and the natural colour of sulphur is greenish yellow- PLUMBAGO. Plumbago, black lead, graphite, or carburet of iron, is a mineral composed of about 90 to 95 per cent, of carbon with the remainder in the per cent, of iron. Although anthracite approaches it in its com- position, being usually pure carbon with a smaller pro- portion of iron, they are sufficiently characterised and distinguished by their physical properties.— Black lead soils the hands, and gives the well known ( 284 ) mark on paper. But there is another mineral which resembles, and has been taken for graphite ; this min- eral is known by the name of sulphuret of mobyb- denum, and is not so abundant as the black lead.— The mark of the two on porcelain; the agency of sulphuric acid, he. will point out the difference be- tween them. Plumbago is infusible and burns with great diffi- culty. In consequence ofthe action of muriatic acid on the iron and clay, which often contaminate plumba- go, Messrs. Berthollet and Scheele availed them- selves of this method of purifying it. The liquor be- ing decanted after digestion upon the plumbago, the residue is then washed, and submitted to distillation to separate the sulphur. Ten parts of nitrate of pot- ash, and one part of plumbago, projected into an ig- nited crucible, will deflagrate, and leave carbonate of potash, and a small portion of oxyde of iron in the crucible. These proportions were adopted by Chaptal. Besides the use of plumbago for the making of pencils, which should in fact be- nothing more than plumbago sawed into pieces, and in the manufacture of inferior pencils by kneading it with mucilage, or fusing it with sulphur, a fraud easily discovered by the assistance of fire, which burns the sulphur, or by means of water which dissolves the mucilage; it is also employed to lubricate certain instruments, po- lish or glaze shot, for razor strops, for the fabrication •of crucibles, lute for retorts when mixed with elay ( 285 ) ind cow's dung, and to defend iron from rust. In 1G99, Homberg communicated a process for per- serving iron from rust, which has been found ex- tremely useful. It consists in making a mixture of 8 lbs. of hog's lard, by melting it with a little water, with four ounces of camphor, and after removing the mixture from the fire, adding, while yet hot, a fraall quantity of plumbago, to give it a leaden colour.— The utensils must be heated to such a degree, that the hand can.scarcely be applied to them. In this state the composition must be rubbed on, and afterwards wiped when the piece is dry. As plumbago which is used to defend iron from rust, and for other purposes, is always sold in a ground state, it should be entirely free of any adult- eration. If it contain lamp black, the mere expo- sure to heat will burn it off. It is sometimes, how- ever, necessary to identify, as well as judge of the purity of black lead. This may be effected by pro- jecting it on red hoi nitrate of potash, in a crucible, which will produce a detonation in consequence of the carbon ; then dissolving the decomposed nitre, and collecting the oxyde of iron, and ascertaining its weight. It should not exceed 10 per cent. We may also remark, that the quantity of carbon in the graphite may be known, since 12.709 of carbon are required to alkalize 100 of nitre. { 286 ) INDELIBLE INK. Genuine durable marking ink should be compound of a solution of nitrate of silver, and carbonate of se*- they will not L- volatilized like the salts of ammonia. If the acid contained ( 328 ) tion 0/ the chlorate. The chlorate of potash should be entirely free from it. It may be detected by adding to a solution of the chlorate in water, a few drops of nitrate of silver, which will occasion a white precipitate, (chloride of silver,) but with the pure chlorate no effect will take place. It is extremely difficult, however, to separate the whole of the chlo- ride of potassium; and even with the purest, some- traces may be found. Chlorate, formerly hyperoxymuriate of potash, is prepared by passing a current of chlorine gas through a solution of caustic potash, either by means of Woulfe's apparatus, Knight's improved apparatus, Hemhel's contrivance, which has many advantages, or any apparatus by which the saturation can be ef- fected. The solution will crystallize, and the crys- tals must be carefully separated from the mother water, which contains muriate of potash. NITRATE OF POTASH. Nitrate of potash, nitre, or saltpetre is received either in a crude, impure, or crystallized state.— in the salt be combustible, it will be decomposed, furnishing a a residue of Carbonate of potash and some charcoal. If incom- bustible, the salt usually fuses; to which, however, there are some exceptions. They are not precipitated by infusion of nut galls, nor by ferrocyanate of potash; but a solution of plati- num throws down an orange coloured precipitate. They are not affected by sulphuretted hydrogen gas, nor by the addition of a hydrosulphuret, except when their acid has a metal for its basis, ( 329 ) Crude or unrefined saltpetre contain a variety of for- eign substances, and the object of the refiner is to separate them. Thus, in rough saltpetre we often find the nitrates of lime, magnesia, and soda, and muriates and sulphates of the same substances, which exist, however, in variable, and uncertain quantities. It is easy to satisfy ourselves of this fact. When crude or rough saltpetre is dissolved in water. the soluble salts will be taken up, leaving very fre- quently a copious sediment, consisting of sulphate of lime, oxyde of iron, &c. If the solution is filtered, aid examined with nitrate of barytes, sulphuric acid will be shown ; if examined with nitrate of silver, muriatic acid; and if with carbonate of potash, the firesence of earths. We may remark, however, that ihe earthy salts are less frequent, because the potash used in extracting the saltpetre in the first operation, not only converts the earthy nitrates into nitrate of potash, but also the earthy muriates and sulphates in- to the salts of that alkali. IlA rude saltpetre should consist of a mixture of nitrate of potash and muriate of soda, it is evident, that its purification would depend altogether on the reparation of the muriate; but as it is difficult to sep- arate the whole of the muriate, even in the best re- fined saltpetre, traces of muriatic acid are always de- tected. Solution of pure nitre »either precipitates nitrate of silver, nor nitrate of barytes. These tests it is obvious, show the presence of sulphuric and mu- riatic salts. The quantity of muriate of soda may be learned by weighing the precipitate, if any be produced by the nitrate of silver ; for every hundred ( 330 ) grains, when washed and dried, will denote about 42 1-2 of muriate of soda. Nitrate of potash when decomposed by sulphuric acid, should produce nothing in distillation but nitric acid ; and when fused in a crucible heated to red- ness, and deflagrated by charcoal, the residue should consist of carbonate of potash, without any earth, metallic oxyde, sulphur, or soda. Nitrate of potash is found native, and is also the pro- duct of art. In the artificial nitre beds, from which nitre is extracted by lixivation, there is a mixture of animal and vegetable substances, with old rubbish. calcareous earths, he. By the concurrent putrefac- tion of the animal and vegetable matter, nitric acid, besides the usual products of putrefaction, is genera- ted, which attaches itself to the alkalies and earths existing in the bed. It appears that the azote, at the moment of its liberation from the animal matter, and probably by the decomposition of ammonia, also generated, unites with the oxygen ofthe atmosphere. and forms nitric acid. Nitre atone time was altogether made in France by artificial nitre beds. It is extracted by lixiva- tion with wood ashes, the alkali of which decompo- ses the earthy nitrates, &c. and refined by solution, further addition of potash, filtration, evaporation, and crystallization. Double refined saltpetre- is that which has been treated a second time in the same manner. If saltpetre should become moist in the air, it is a sure indication of the presence of deli- quescnt salts, as muriates of lime and magnesia, and ■( "l ) n.it it has not been properly refined. Gun powder made with saltpetre of this description, as well as in other respects impure, wouid be either unfit for use. or very inferior in its [tower. So: Gun Powder. In the United Slates there are several caves or caverns of considerable extent, which contain an nbundance of nitrous earth. These caves exis' mostly in the Western country, and have ahead} ielded immense quantities of saltpetre. \iirate of potash has occasionally been found in acm ; but the nitric acid, for the greater part, isunit- ed with lime, forming nitrate of lime, or calcareous nine. From the vast extent of these caverns, and the inexhaustible supply of nitrous earth, we may feel assured, that in the article of saltpetre, so es- sential in warfare, no deficiency for many centime- will be experienced. The extraction of saltpetre is performed by merely lixivating a mixture ofthe earth and wood ashes, by which the acid of the ni- trate of lime unites with the potash ofthe wood ash- es, and the lime with any carbonic acid from the ashes remains with the insoluble substances. The nitrous liquor, thus obtained, is boiled down, and constitutes the saltpetre of the first boiling. This altpetre, like that obtained from artificial nitre beds, is very impure ; and requires to be thoroughly refined before it is fit for the manufacture of gun powder. .Many remarkable facts are connected with these saltpetre caves. One which has appeared to me a« the most striking is, that after every particle of ( u32 ) saltpetre has been extracted from ihe earth, il the same earth be placed in the cavern it will in a short lime yield as much saltpetre as before. There must be something peculiar in the earth, which has evaded all research, or something in the atmosphere of the cavern more than what is known, to produce this singular effeot. If the earth furnishes nascent azote, we may then account for the generation of ni- tric acid by its union with the oxygen of the atmos- phere. The origin of nitrate of lime, in caverns, is alto- gether inexplicable in our present state of chemical knowledge. In Georgia, at Nicajack, in Racoon Mt. is a-cav- ern which contains the nitrate both of potash and lime; one bushel of the earth yields from three to ten pounds of crude nitre. The cavern in Madison county, about 60 miles from Lexington yields, in the bushel, from one to two pounds of nitre. The rock ore of Kentucky is a sandstone richly impregnated with nitrate of potash, one bushel of which frequent- ly affords ten pounds and sometimes twenty pounds of nitre. The nitre obtained from these rocks is al- most wholly free from nitrate of lime, and is prefer- red for the manufacture of gun powder. Masses o\ native nitre weighing several pounds, are occasion- ally found in the fissures of these sand stones. Cal- careous caverns, containing nitre, occur in Ohio, Tennessee, and in some parts of Virginia and Mary- land. Dr. Mitchell says, in*a note to Philip's Minerolo- ( 333 ) gi,, p. 115, that " during the late contest with Great Britain, the saltpetre of Kentucky was brought abundantly to New-York, for the powder mills."— See Med. Repos. vol. 9, p. 86—88. Nitrate of potash is recognised by placing it on hot coals. Whether pure or mixed with earthy or saline substances, a vivid combustion, accompanied by a hissing noise and slight detonations, will take place. It sometimes occurs native in the form of an efflorescence or a crust, and substanees to which it adheres often have a mouldy appearance. Nitrate of lime has a sharp and bitterish taste, and is also found on the surface of the earth in efflorescences, or in delicate needles. On burning coals it slowly melts, and, as it dries, slightly detonates. From nitrate of potash it is distinguished by its taste, and the addition of oxalate of ammonia to a solution in water. This salt almost always accom- panies nitre, and appears in fact to be formed along with it, when circumstances are favourable. In the immense deserts of Persia and Arabia, for the space of seven hundred miles, travellers inform us, that the quantity of nitre and other salts is so con- siderable as to impregnate very sensibly the neigh- bogring Jakes and rivers, and has, on that account, been denominated the Great Sali?ie Desert. During the American revolution, every effort was made to obtain nitre. Such was the zeal and indus- try, at that time, that, as Dr. Black assures us in his Lectures, the floors ofthe tobacco houses were dug •and lixivated. The late Dr. Rush, one of those ( 334 ) inflexible patriots who signed the Declaration of In dependence, informed me, that numerous essays were written at that period, on the different means of obtaining saltpetre; and notwithstanding the dif- ficulties encountered, and the scarcity of the article, the supply soon became sufficiently ample. The same zeal was subsequently manifested in France, in the institution of saltpttre works in the different de- partments, and the instruction of young men in the processes of extracting and refining of saltpetre. SULPHATE OF POTASH. The salt which remains in the retort, after the dis- tillation of nitric acid from nitrate of potash by sul- phuric acid, is sulphate of potash. There are two sulphates; the neutral and the bisulphate. The lat- ter usually remainsafter the distillation of nitric acid, and, therefore, to make the neutral sulphate, it is necessary to saturate the excess of acid with potash. Sulphate of potash, or vitriolated tartar should be free from any foreign salt, and excess of sulphuric acid; which may be known as well by the taste, as its action on the tincture or infusion of litmus. When this salt is healed with charcoal, it produces sulphur- et of potash. CARBONATE OF POTASH. Carbonate of potash, subcarbonate of potash, sai: of tartar, and salt of wormwood, are synonimour ( 330 ) terms: and imply the purified, and generally the granulated carbonate of that alkali sold by the apoth- ecaries. Its most common appellation is salt of tar- tar; a name given to it in consequence of being pre- pared from tartar. It is the alkali of tartar. We have already spoken of the method of ascertaining the quantity of absolute alkali in pearlash, potash. and barilla of commerce. It remains to point out the usual method of examining the carbonate it question. The solubility of salt of tartar, like the alkalies generally, is very considerable; and its attraction foi water is so great, in common, however, with caustic potash, that when exposed 10 the atmosphere, it will absorb it, and run per deliquium. If pure, it should dissolve in twice its weight of cold water ; any inso- luble matter is an impurity. Frequently an insolu- ble residue equal to one fourth remains, consisting of sulphate of potash. The nature of the adulteration will be shown by dissolving the sediment in diluted nitric acid ; the siliceous earth only will remain un- dissolved. By using the nitrates of barytes and sil- ver, we may delect sulphuric and muriatic acids, and oxalic acid or oxalate of ammonia, will determine the presence of lime. One hundred parts of nitric acid specific gravity 1.36, will saturate seventy parts of dry carbonate of poiash, winch are equivalent to for- ty-eight parts of pure potash. ( 336 ) BICARBONATE OF POTASH. ^ The other salt formed by the union of potash anc carbonic acid, is the bicarbonate. It is formed by passing a current of carbonic acid into a solution of the common carbonate ; or, according to a more ex- pensive method, by the action of carbonate of am- monia on carbonate of potash. This salt crystallizes in four sided prisms, with dihedral summits. They require for their solution four parts of water at 60 degrees. It is sometimes used in preparing extem- poraneous aerated alkaline water. Its purity may be judged by its taste, which should be slightly alkaline; by its crystallization ; by its degree of solubility; by the quantity of carbonic acid it contains; and, gene- rally, by the use of the reagents mentioned in the preceding article. We may add here, in relation to the precipitates, that 100 parts of sulphate of barytes are equivalent to 74 of sulphate of potash, 100 of muri- ate of silver are equivalent to 62 of muriate of potash, and 100 of oxalate of lime are equal to 77 of car^ ate of lime. ACETATE OF POTASH. When potash is saturated with acetic acid & salt is formed) called in the old pharmacopeias the febri- fuge salt of Sylvius and diuretic salt. The acetate of potash is soluble in four times its weight of alco- hol, by which it may be separated from other salts that are insoluble in that fluid. 0 ( 337 ) 1'he foreign salt most likely to contaminate it is the neutral tartrate of potash, or soluble tartar; which is -'-cognised either by the addition of tartaric acid p'»dtic ■ precipitate, or by adding acetate of lead 01 m i. .. barytes, either of which will give a precipitate soluble in acetic or muriatic acid. Sul- phates are detected by the last mentioned tests, but the precipitate in that case is insoluble in nitric or muriatic acid. Acetate of potash is soluble in its weight of water at 60 deg. and the solution has a sa- line acid taste. SULPHURET OF POTASH. When potash is fused in a crucible with a given quantity of sulphur, a compound results, which has been long known under the name of liver of sulphur. This sulphuret of potash should 'contain no lime, which may be known by dissolving it in water, and adding the reagents for that earth. Liver of sulphur is very deliquescent, and very soluble in water, form- ing the hydroguretted sulphuret of potash, a com- pound of supersulphuretted-hydrogen, or hydrogu- • retfed sulphur with potash. This is altogether dif- ferent from that preparation, which is formed by passing a current of sulphuretted hydrogen gas through a solution of potash, as the latter, correctly . speaking, produces a hydrosulphuret of potash.— These two compounds may be distinguished by ni- tric acid: with the hydroguretted sulphuret of pot- ash, it gives a copious precipitation of sulphur, but 29 ( 338 ) % with the hydrosulphuret, if properly made, no pre- cipitate. Sulphuret of potash should be kept as dry as pos- sible. When breathed upon, there is instantly a foo- ted odour, like that of rotten eggs, which will colour a silver spoon almost immediately. This is owing to the decomposition of the moisture, and the evo- lution of sulphuretted dydrogen gas. When sul- phuret of potash is dissolved in water, a hydroguret- ted sulphuret, with sulphate or sulphite of potash is produced. It is from the sulphuret of potash, by so- lution in water and the addition of sulphuric or mu- riatic acid, that the milk of sulphur is produced, which is a hydrate of sulphur. SULPHITE OF POTASH. Potash when combined with sulphurous acidfornifa the sulphite of potash; a salt which, by exposure to the air, changes rapidly into the sulphate. Should that be the case, it may be known by using the lest for sulphuric acid. This salt is readily formed by passing sulphurous acid through a solution of pot- ash. Sulphurous acid gas has been long used for bleach- ing ; woolens, straw bonnets, he. are whitened by the fumes of burning sulphur, and the effect is owing to the production of this acid. Sulphurous acid, es- pecially when united with alkalies, unites with oxy- gen, and is changed into sulphuric acid. It is sometimes found in natural waters, and gives ( 339 ) them the smell of burning sulphur. If a few grains of the black oxyde of manganese be put into a piiial of water containing this acid, it will loose its pecul- iar smell in a short time, owing to the combination >l the acid with the oxygen of the oxyde. This is me of the means recommended for recognising the preseuce of this acid in a mineral water. By the action of sulphuric acid on some of the metals, as lead or mercury, in the formation of me- tallic sulphates, sulphurous acid gas is liberated in abundance. SAL PRUNELLA. Nitrate of potash when fused and cast into moulds, orms sal prunella. It is nothing more than salt pe- tre deprived of its water of crystallization. The fu- sion should be conducted carefully, and in a heat be- low redness; if higher, the salt petre will be decom- posed, and furnish oxygen gas and nitrite of potash; and if the heat be white, the products would then be oxygen, azote, and dry potash. Some sprinkle the nitre, when in fusion, with sulphur; which must con- taminate the sal prunella with sulphate of potash. This salt may be known by dissolving the sal pru- nella in water, and adding nitrate of barytes. Muri- ate of soda may exist in it, inconsequence ofthe im- purity of the salt petre, ( 340 ) TARTRATE OF POTASH. When the excess of acid in cream of tartar, or su pertartrate of potash, is saturated with potash, the neutral tartrate of potash, commonly called soluble tartar is formed. This salt is immediately affected by tartaric acid. Hence it should afford a copious precipitate with tartaric acid,and produce the supertar- trate. Sulphate of soda is sometimes used to adul- terate it. It may be detected in the usual manner, by solution in water, and the addition of muriate of barytes. The sulphate thus produced, should be in- soluble in diluted muriatic acid. According to Mr. Richard Phillips, 100 parts of tartar require 43.5 of carbonate of potash for satura- tion. TARTRATE OF POTASH AND SODA. When the excess of acid in cream of tartar is sat- urated with carbonate of soda, the triple tartrate of potash and soda is formed; a salt formerly called Sel de Seignette, and now Rochelle salt. It forms irregular prismatic crystals. This salt is composed, according to Vauquelin, of 54 tartrate of potash and 46 of tartrate of soda per cent. Of foreign salts, sul- phate of soda is the most likely to be found. This adulteration may be detected by dissolving the Ro- chelle salt in water, and adding acetate of lead or muriate of barytes. If the sulphate be present, the former will give a precipitate of sulphate of lead in- ( 341 ) soluble in acetic acid; and the latter a precipitate nsoluble in muriatic acid. SUPERTARTRATE OF POTASH. This salt called also the bitartrate of potash, and known by the familiar name of cream of tarter, is o- riginally deposited from the must, or juice of grape either during its fermentation, or in the casks con- taining the wine. The deposit is more or less crys- tallized, and usually red; hence the red tartar of commerce.* It is, however, more commonly cal- led argol or crude tartar. The must of grapes (of the vttis vinifera of Linnaeus) contains, as we have observed, a considerable portion of saccharine mat- ter, which furnishes alcohol by fermentation, and an acid, principally the tartaric unjted with potash. In the fermentation a redundancy of tartar is precipita- ted, and also by the standing of the wine. The tar- tar is coloured in consequence ofthe colouring mat- ter contained in the husks, he. ofthe grape, which is frequently taken up intentionally by suffering the fermentation to take place on the skins, thus giving rise to the different red wines. Crude tartar is purified by solution, filtration, and crystallization, and then becomes white. It is now * Tartaric acid has been found in a variety of vegetable sub- stances, besides the juice of grapes. We shall name a few of thein, viz. the pulp of th* tamarind, the rhus typhinum, vacci- nium oxycocts, rheum raponticum, morus alba,pxnus syivestris, abies and larix, leontodon taraxicum, he. 29# I o42 ) the crystals of tartar, and when pulverised takes the name of cream of tartar. The bitartrate of potash is a salt of very difficult solubility, requiring 120 parts of water at 60 degrees, and 30 parts at 212 degrees for its solution. In consequence of this great, comparatively speaking, insolubility of the super or bitartrate, we perceive why tartaric acid precipitates potash from its solu- tion by the immediate formation of supertartrate of potash, and why, therefore, it is employed as a rea- gent for that alkali. With soda, on the contrary, it forms a supertartrate of easy solubility, which does not precipitate. The crystals of tartar may be adulterated by sul- phate of potash. This is detected as follows : pour on half an ounce ofthe powdered crystals, two or three ounce measures of distilled water, and, after shaking the mixture frequently, let it stand undistur- bed. The sulphate of potash being more soluble will be taken up, leaving the supertartrate. The so- lution will have a bitter taste, and, on adding muri- ate of barytes, will give a precipitate insoluble in muriatic acid. If a solution of the tartar be made in hot water, and the same reagent added, the same effect will ensue; but the precipitate, as before, must be inso- luble in muriatic or nitric acid. In the powdered crystals of tartar, or cream of tartar, besides the presence of sulphate of potash, we may frequently detect sulphate of soda. A little of the tartar thrown into water, will, if sulphate of so- ( M ) da is present, be immediately dissolved, which is known by its taste, and the addition of muriate of barytes. If there be reason to suspect the admix- ture of calcined plaster of Paris, (although we have never known that adulteration,) the fraud maybe de- lected by dissolving the tartar in a large quantity of water, and the precipitate or sediment examined for . tartrate of lime, as well as the solution for lime, and of course, for sulphuric acid ; as a part of the sul- phate of lime may be found in solution, and also in consequence of the decomposition, some sulphate of potash. PURE SODA. Pure soda, by which we mean the alkali free from any foreign substance, may be tested in the same manner as pure potash. It may contain potash, the discovery of which is effected by adding to its aque-' ous solution muriate of platinum, which will form a buffcoloured precipitate, if it be present. Muriate of platinum, in such cases, produces a triple com- pound of potash, oxyde of platinum, and muriatic acid. When soda is exposed to the air, it soon becomes covered with an efflorescence of carbonate of soda. Soda may be distinguished from potash ; it forms an efflorescent paste, while potash under the same cir- cumstances deliquesces. If excess of tartaric acid, we remarked in our pre- ceding subject, be added to a solution of soda, no ( 344 ) precipitation will take place, whereas in a solution ol potash it occasions a copious precipitate consisting of minute crystals of tartar. But these facts have been fully stated heretofore. SODA WATER. Water was a long time impregnated with carbonic- acid gas by means of Nooth's apparatus ; and alka- line solutions were aerated by the same contrivance. In consequence of the acidity, briskness, and pun- gency, added to the medicinal effects of certain na- tural waters containing carbonic acid, their imitation has been attempted. Soda water, however, is no- thing more than water holding in solution about 8 or 10 grains of soda or mineral alkali to a pint, and charged usually with three or four times its bulk of carbonic acid. Water merely surcharged w7ith car- bonic acid, is more frequently sold as soda water; but soda water is decidedly more beneficial than the mere aerated water, although the latter contains all the carbonic acid, and is very agreeable as a bever- age. By the usual contrivance for impregnating fluids with gases, it is impossible to combine a sufficient quantity of carbonic acid ; hence an expedient has been adopted, which not only saturates the water and the alkali, but surcharges the whole in an eminent degree. This contrivance consists in using a forcing pump, and pumping the gas from a gasometer, and forcing it into a copper vessel tinned in the inside, ( 345 ) which contains the alkaline solution. This is the present mode of preparing soda water. The prepar- ation of other waters, which contain carbonic acid^ is effected in a similar manner, proportioning the carbonic acid gas accordingly. iErated waters when drawn from the fountain, should foam considerably, a criterion that the water has been well charged with carbonic acid; But to determine whether the water actually contains soda^ it is necessary to examine it chemically. For this purpose a portion of the water may be evaporated, and the residue, if alkaline, will be known by its taste. A portion of sulphuric acid poured on it will occa- sion an effervesence ; and the salt, when crystallized, will exhibit the characters of Glauber's salt. Water containing alkali in solution, it is admitted, will receive more carbonic acid than the plain wa- ter. We mentioned in a former lecture, that when so- da water is allowed to remain any length of time in the copper vessels, especially if they are imperfectly tinned, or the tinning worn off, it is liable to contract a portion of copper. Water, however slightly im- pregnated with copper, is in a degree deleterious, and frequently occasions vomiting, or pain in the abdominal viscera. If water of ammonia be added to the suspected water, copper will be detected by the mixture becoming more or less blue. The pre- .-ence of lead may be known by aqueous sulphuret- ted hydrogen, or Hahneman's wine test, which will give a dork brown precipitate. ( 346 ) Extemporaneous soda water is now prepared by using a vegetable acid with bicarbonate of soda.— They are put up in boxes, contained in separate pa- pers. When the two are dissolved, alternately, in a glass of water, a disengagement of carbonic acid gas takes place, occasioned by the action of the acid on the carbonate. Soda powders, when properly made, and kept from the moisture ofthe air, are an excel- lent substitute for soda water. At sea, in particular, they must prove very beneficial. There are several manufacturers of these powders, none of which, however, are superior to those of Lynch and Clarke, Wall-street, New-York. If the bicarbonate of soda is properly prepared. the soda powders, must, of course, be good. The proportion of alkali and acid in each paper, which is designated from each other by the colour of the paper, is about ten grains, and this quantity is used for a half pint tumbler. It is to be observed, that in the action of the acid on the alkaline carbon- ate, a salt is produced, which remains in solution : if the acid be the citric, which is usually the cise, the salt is then a citrate of soda. Sometimes sirup is used to impart" a more agreeable taste, and at the same time to prevent the rapid disengagement ofthe fixed air. It is better to dissolve the powders in separate glasses, with each half full of water ; and to mix them in one glass as quickly as possible. If 320 grains of bicarbonate of soda be dissolved in a pint of water, a table spoonful of the solution will contain ten grains ; and if in another pint of wa- ( 347 ) icr twice the quantity of the bicarbonate of potash be dissolved, viz. 1 1-4 oz. and 4 scruples, the so- lution will then contain twenty grains in a table- spoonful. Now the quantity in each, admitting that ten grains of the soda is the usual proportion in a glass of soda water, will make thirty-two glasses.— By putting a spoonful of each in separate tumblers, filling them nearly half with water, and mixing them briskly, extemporaneous soda water will be made in the most expeditious manner. The excess of acid in the bitartrate of potash will be sufficient, or there- about, to neutralise the soda; and the salt, which will result by the union ofthe two, is the tartrate of potash-and-soda, or sal Rochelle; the quantity, how- ever, being so small as not to act as a cathartic. As the proportion of acid is not material, and the acid generally, but especially the vegetable, may be us- ed ; a very pleasant beverage, partaking also of the character of sirup, a«i addition which is frequently made, may be prepared by substituting the lemon si- rup. The citric acid will act on the bicarbonate ; carbonic acid will be disengaged, which will be pre- vented from escaping, or at least not so rapidly, by the saccharine matter of the sirup ; and citrate of so- da will be formed. This method of producing sweetened araied soda water has advantages. ( 348 ) MURIATE OF SODA * Sea salt, common salt, muriate of soda, hydro* chlorate of soda, or chloride of sodium, terms which are used to e.-oiress ibe seme sail, is scarcely jver found JKc O'ooa e. - so • , w ■ eii are chiefliy mu- riates of lime and magnesia. They are usually con- tained in the brine and adhere to the salt. li is to the presence of foreign salts, and principally the earthy muriates, that some salt is so feeble in its ef- fect as a preservative to meat, and often so injurious to beef in particular. They appear to injure, -js well as retard, the antiseptic properties of the pure salt. Some of the salt made in this country is of this de- scription. Salt, however, which contains these mu- riates, is generally humid or moist, owing to their deliquescence. After ascertaining the fact by ex- *The salts of soda are more soluble than the salts of potash. Many of this class of salts contain a large quantity of water When exposed to a red heat, they usually speedily melt, and, finally, when all the water is driven off, the salt appears in a -*hite powder. If the acid be combustible, it is destroyed ; but if it be fixed, the salt melts again at a red heat. The shape of the crystal, will readily determine the base of the salt; or, if its crystallization is irregular, the salt may be decomposed by sul- phuric acid. Sulphate of soda is easily recognised by the shape of its crystals, so is also nitrate of soda. Salts of soda are not precipitated by tartaric acid, nitroinuriate of platinum, infusion of galls nor ferrocyanate of potash. The two last, however, will produce, a precipitate if the acid has a metallic basis. With the salts of soda, sulphate of alumina does not produce octahe- dral crystals of alum, as with the salt of potash, another very distinguishing character. ( 349 ) pertinent, the best mode of getting rid of these im- purities is by re-dissolving the salt, and again boil- ing it, carefully separating the mother water. Ano- ther mode may be resorted to, but more expensive, viz. by adding a due quantity of soda, filtering the solution, and evaporating it to dryness, by which the earthy muriates will be decomposed, and chan- ged into muriate of soda. The mother water, at all times, should be carefully separated from the salt. The common salt of commerce is not sufficiently pure for the purposes of chemistry. It may be im- perfectly purified by repeated crystallizations. But the following process will effectually purify it. Dis- solve it in four times its weight of water, and filter the solution; first add muriate of barytes, then of car- bonate of soda, as long as any precipitate continues to fall. Separate the precipitates by filtration, and evaporate slowly till the salt crystallizes. The ocean is the great depository of common salt. for nearly one thirtieth part of its weight is muriate of soda. Immense beds of sal gem or rock salt are found in some countries. Magnesia and lime may be separated by making a solution of salt in water, and adding carbonate of potash. If 100 grains be dissolved in an ounce of water, and carbonate of ammonia added, carbonate of lime, if the salt had contained muriate of lime, will be precipitated. Of this precipitate, 100 parts when washed and dried, at 300 degrees, are equivalent to 110 of dry muri- ate of lime, or chloride of calcium. If the filtered liquor be now boiled nearly to dryness and magne- ( 350 ) sia be contained in it, the carbonate of that earth will fall; 100 parts of which are equal to 134 of dry muriate of magnesia. Sulphate of magnesia or sul- phate of soda may be detected by using the test for sulphuric acid ; and if a solution of the salt be evap- orated and crystallized, crystals of Glauber's salt will be readily recognised. Carbonate of ammonia, added to the fluid, will retain the magnesia in solu- tion, which will be precipitated by phosphate of so- da, SULPHATE OF SODA. Sulphate of soda, or Glauber's salt, being one of the cheapest salts, is seldom, if ever, adulterated. It should be perfectly neutral, and, therefore, not af- fect either litmus or turmeric paper. In a crystalli- zed state it contains about 56 per cent of water. If, it contains iron, the fact may be known by tincture of galls, or ferrocyanate of potash ; if muriate of so- da, with which it is frequently contaminated, by sul- phate of silver; and if salts of lime, by carbonate of ammonia. Sulphate of potash is recognised by its sparing solubility. Effloresced salts are as active a$ the crystallized. One half the quantity is sufficient for a dose. Glauber's salt is manufactured from the mo- ther water of sea water,by the combustion of the tamar- ix gallica, and is the result of several chemical pro- cesses. Thus, it is formed in the distillation of mu- riatic acid from muriate of soda by sulphuric acid ; in the sublimation of sulphate of ammonia and muri- ( 351 ) ate of soda, for the preparation of corrosive subli- mate and calomel; in the calcination of sulphate of lime, muriate of soda and clay, he. besides by the combustion of certain maritime plants. Having noticed the preparation of Glauber's salt from sulphate of lime, an article so abundant and cheap, it may not be improper to mention the pro- portions of the substances used, as given by Funcke. Eight parts of calcined sulphate of lime (gypsumj five of clay, and five of muriate of soda, ('common salt,) are made into a paste in water, then burnt in a kiln, and the mass taken out and powdered; it is then lixivated, and the solution evaporated, and set aside to crystallize. This is unquestionably a very economical method of preparing Glauber's salt. We see, however, no particular advantage in using cal- cined gypsum, inasmuch as water is added to form the paste; and, therefore, the ordinary powdered plaster, which is strewed over land, will answer the purpose. Calcined gypsum, as it absorbs water, and becomes hard in a short time, may on that account be preferable. Glauber's salt is manufactured in the eastern states from the mother water of sea water, after the separation of common salt; hence it con- tains muriate of soda, frequently sulphate of magne- sia, and is generally imperfectly crystallized. CARBONATE OF SODA. Carbonate of soda of the shops, or subcarbonate of soda of the Pharmacopeias, often contains sul- ( 352 ) phate and muriate of soda. Kelp and barilla belong to this class of alkalies. This may be examined in the same manner as potash and pearl ash of com- merce, if we wish to determine the quantity of real alkali. To discover the presence of sulphate and muriate of soda, we must first saturate a given weight of the 3oda pure dilute nitric acid ; and to one portion add nitrate of barytes, which will give a precipitate of sulphate of barytes, and to another portion nitrate of silver, which throws down muriate of silver; 100 parts of which are equal to 41 of sea salt. Carbonate of potash may be detected by adding to a saturated solution ofthe carbonate, tartaric acid in excess; bitartrate of potash will precipitate in crys- talline grains. BICARBONATE OF SODA. The bicarbonate of soda, which is usually formed by passing carbonic acid through a solution of the ordinary carbonate, contains 32 per cent, of soda, and 44 per cent, of carbonic acid. It has a slightly alka- line taste. This salt is largely used in preparing the extemporaneous aerated soda water. A mixture of the two carbonates occur native, but in an impure state. Thus, it occurs in Africa, in several lakes, he. and is usually called Trona. Natron and mineral alkali are the same as soda. As respects the bicarbonate, it is frequently contam- inated with the carbonate of soda: it is difficult, how- ( 353 ) ever, to detect it. The best criterion would be the quantity of carbonic acid liberated, and the loss which the salt sustains on saturating it with a given weight of acid. The native bicarbonate of soda, called trona, found in the province of Sukena, is crystallized in hard striated masses, and is not alter- ed by exposure to the air. The common carbon- ate of soda forms large beautiful crystals. SUBBORATE OF SODA. Subborate of soda or borax, called in its impure state tincal, contains when pure, about 34 per cent. of acid. It is decomposed by sulphuric acid, and furnishes boracic acid. It is sometimes adulterated with common salt, and alum. The fraud may be de- tected by dissolving a portion of the salt in water, saturating the excess of alkali with nitric acid, and adding respectively nitrate of silver and nitrate of ba- rytes. The alumina may be thrown down by am- monia. NITRATE OF SODA. Nitrate of soda, or cubic nitre crystallizes in rhombs. It is often found in crude nitre, and nitre sometimes occurs in it. The presence of nitrate of potash may be shown by muriate of platinum, which will detect the potash. The sulphate and muriate of soda may be detect- ed as before mentioHed ( 354 ) PHOSPHATE OF SODA. Phosphate of soda, or soda phosphorata, is pre pared by saturating phosphoric acid with soda. Its crystals contain about 60 per cent, of water, and when heated it loose* its water of crystallization, and melts into a glass. If a globule be heated before the blow pipe, it assumes the dodecaedral figure as it cools. This salt, although not usually adulterated, may be examined for foreign salts by the tests before men- tioned. The whole of the phosphoric acid may be separa- ted by using sulphate of magnesia, and carbonate of ammonia, as heretofore noticed. As phosphoric acid is thus separated, and phosphate of soda em- ployed as a reagent for detecting the presence of magnesia, after the addition of carbonate of ammo- nia; the precipitate formed, in such cases, will de- termine the relative quantity of each substance.— One hundred grains of the precipitate will indicate 19 of pure magnesia; 44 of carbonate; about 66 of muriate of magnesia; and 62 of dissicated,or double that quantity of crystallized sulphate of magnesia.— If the precipitate be calcined, the phosphate of mag- nesia will indicate 38.5 of magnesia, or equivalent to 22.6 grains of the crystallized sulphate of magne- sia; and every hundred parts will indicate about 61 per cent, of phosphoric acid. The ammoniaco phosphate of magnesia, (the trip- le salt which is thrown down,) contains according tr.< ( 355 ) Fourcroy, equal weights of phosphate of ammonia, phosphate of magnesia, and water. SUPERSULPHATE OF ALUMINA AND POTASH, ALUM* Supersulphate of alumina-and-potash alum, is pre- pared in several ways, either by roasting certain clays, or argillites, which contain pyrites, he. and lixivating them in the usual manner, with the addition of pot- ash ; or by the direct union of alumina and sulphu- ric acid, and treating the lixivium in the usual mode. The observations of professor Cleaveland (Ele- mentary Treatise on Mineralogy and Geology,) on * Most of the salts of alumina are soluble in water. They have an astringent taste ; are not precipitated by oxalate of am- monia nor by tartaric acid,like the salts of y ttria; neither are they affected by ferrocyanate of potash, nor by tincture of galls, which distinguish them from the salts of glucina and yttria. Phos- phate of ammonia produces a white precipitate, and hydriodate of potash a precipitate which becomes yellow, and continued permanent. When sulphuric acid, and1 then sulphate of pot- ash, are added to a salt of aluminaj octahedral crytals of alum will be formed. Alumina is recognised before the blow pipe, if it be not com- bined with a large proportion of metallic matter, or of magne- sia, by forming with a drop of nitrate of cobalt a bright blue co- lour. It may be discovered in this manner in the agalmato- lite. Alumina combines more slowly with the fluxes than the other earths, and forms a clear gloss, which does not become opaque- ( 356 ) the modes of obtaining alum are perfectly correct; viz. that if salt exists, already formed, in earths or fri- able minerals, it is extracted by lixivation; but, if the mineral be solid, it must be previously calcined. Thus, if the alum stone of La Tolfa be merely lixi- vated, it yields no salt; but, after calcination, it be- comes disentegrated by the gradual action of mois- ture and the heat ofthe sun, and then yields its alum by lixivation. When minerals of an argillaceous nature, contain pyrites or sulphuret of iron, and are roasted, the sul- phur is acidified by the oxygen-of the air, which may be gradual; but the sulphuric acid, thus pro- duced, does not unite with the iron—it combines with the alumina. When the argillaceous mass is sufficiently disente- grated, the alum is extracted by lixivation, a due quantity of potash is added, and the salt is crystalliz- ed. ' Alum has been manufactured in a very large quan- tity by Dr. Troost, in Maryland, at Cape Sable. It is produced by the decomposition of pyrites, &,c.— Cleaveland describes the process as follows : "At Cape Sable, large quantities of pyrites occur in a bed of earthy lignite, from 5 to 12 feet thick, and covered by a sandy alluvion from 15 to 20 feet thick. This ore, being collected into heaps 10 or 12 ft. high, and covering from 4000 to 5000 square feet, soon takes fire; after an interval of 12 or 14 months, the remaining mass is lixivated in large hoppers; the so- f 357 > lution, thus obtained, is concentrated by boiling; potash is added, and alum obtained by crystalliza- tion. These works have yielded annually about 120 tons of alum." The presence of pyrites, or sulphuret of iron, ir coal, has frequently occasioned spontaneous combus- tion. Sulphuret of iron, it is known, will absorb ox ygen, and, while the sulphur is acidified and the iron oxydized, for the formation of sulphate of iron. if the decomposition takes place in contact with coal. the caloric which is put into a distributable state will set it on fire. The same phenomena ensues in the instance above mentioned, where lignite, in con- tact with pyrites, is inflamed. Combustion of this kind produces, by the conver- sion of the sulphuret into sulphate of iron, not alum, but a salt of iron. This, however, is decomposed by alumina, and produces alum with the addition of pot- ash. The veins of pyrites, which produced the more ancient conflagrations of the Phlegrean fields, be- tween Naples and Cuma, and which, in some places, are entirely consumed, are remarkable on account ol this spontaneous combustion. Alum is also manufactured in Salem, Mass. The Salem Observer states, that the works give constant employment for twenty men. Blue vitriol is also manufactured there. But the manufacture cannot be lucrative, if the " importation of most of the raw ma- terials of which it is composed," as the writer in- forms us, is to be depended upon, since it is known, ( 358 ) that at Cape Sable it is prepared in abundance by the decomposition of earthy lignite containing sul- phuret of iron, where no raw material is necessary to be imported. Alum has been made in other parts of the United States by a direct union of its constit- uent parts. The Observer also considers " it a happy coin- cidance that the interests of this establishment (the Salem) and the interests of commerce, are mutually promotive of each other." To this we may remark, that no manufactury in the country can be efficient and permanent, which depends on raw materials •from abroad; we must have them within ourselves, if ultimate success is to crown our labours. Hence the alum works at Cape Sable are permanent, and profitable ; and hence also many other chemical man- ufactories in this country, for the same reason, will stand against all foreign competition. With tempo- rary establishments the principle may answer, but not with a permanent manufacture. Alum is acid, and hence reddens vegetable blues. It furnishes octahedral crystals, but will not crystal- lize without alkali. It is necessary in some of the arts, especially in dyeing, that this salt should be pure, particularly that it ought not to contain either iron, or copper. The former is recognised on add- ing to a solution of alum ferrocyanate of potash, by the production ofthe blue ferrocyanate of iron ; and copper is known by adding an excess of ammonia. The most injurious contamination of iron is sul- ( 359 ) phate of iron. To separate it, Mr. Thenard re- commends dissolving the alum in boiling water, and agitating the solution with rods as it cools.— The salt is thus reduced to a fine granular powder, which being washed two or three times with cold water, and drained, yields a perfectly pure alum. Ammonia may be detected in alum by dissolving it in water, and mixing quick lime wilh the solution, and exposing the mixture to heat in a retort con- nected with Woulfe's apparatus. The ammoniacal gas will be thus collected, and absorbed by water; and the alkaline water, if saturated with an acid, and evaporated to a dry salt, will give the quantity of ammonia. There are several varieties of alum. Thus, if am- monia be used in the place of potash, or along with it, previously to crystallization, we have a supersul- phate of ammonia and ammonia ; and if urine and muriate of potash be used in its fabrication, a variety of alum is formed, which is a mixture of two salts. These bisulphates, if dissolved in water, and treated with gelatinous alumina, will furnish a neutral triple salt, which precipitates in a nearly insoluble state.— This precipitate is what was originally called alum saturated ivith its earth. Cubic alum is considered a fourth variety of alum, and is formed when an unusual quantity of potash is added to alum liquor. Thesaltcrystallizes in cubes, and contains an excess of alkali. The aluminous mordant used by calico printers, ( 360 ) which they mix with starch or gum and apply to stuffs by means of blocks, or stamps, is prepared by decomposing alum by acetate of alumina and sul- phate of lead. The acetate of alumina is preferable to alum for topical dyeing, for sundry reasons. MURIATE OF AMMONIA.* Muriate of ammonia or sal ammoniac, is some- times impure, being contaminated with sulphate of ammonia. This salt, although originally made by sublimation of the soot furnished by the combustion of the faeces ofthe camel, is now prepared chiefly by the decomposition of sulphate of ammonia by muriate of soda. As an article of commerce, it comes in heads or cakes, being formed in that shape by sublimation; but when dissolved in water, and *The salts of ammonia, with but few exceptions, are soluble in water. When mixed with potash or quick lime, they give the smell of ammonia. If a salt containing magnesia be added, and afterwards phosphate of soda, they give a copious white. precipitate. When exposed to heat, they are volatilized, except when the acid has a fixed metal or phosphorous for its base, in which case the acid alone remains. They are not affected by infusion of nut galls, or the ferrocyanate of potash; but they pro- duce with a solution of platinum an orange coloured precipi- tate. As this precipitate is analagous in appearance to that pro- duced by the same reagent with salts of potash, the presence of muriate of ammonia may be readily shown by adding potash or quicksilver, when the well known ammoniacal smell will be- come apparent. ( 361 ) aystallized, it forms octhedral, prismatic, and plu- mose crystals. The purity of muriate of ammonia may be deter- mined by its volatility ; for when heated, it ought to sublime without leaving any residue. If th- re should be any residue, and it is necessary to examine it, the bust mode is to diffuse it in water, which will take up any soluble salt. This solution may then be exa- mined. The residue may be treated with nitric or muriatic acid, and likewise examined for either earths or metals. Sulphate of ammonia, which is volatile, and can- not be detected by sublimation, may be recognised by dissolving the sal ammoniac in water, and adding muriate or nitrate of barytes. If mixed with pure potash or lime and distilled, sal ammoniac should yield ammoniacal gas, and nothing remain in the re- tort but muriate of potash, or muriate of lime. Muriate of ammonia has been found native but containing foreign matter, and is frequently yellow from the presence of sulphur. CARBONATE OF AMMONIA. Carbonate of ammonia presents at least two varie- ties ; the common, sometimes called the subcarbo- nate, and the bicarbonate. The former is the sal volatile ammonia ofthe shops. It is considered by professor Brande as a hydrated carbonate oj ammo- nia ; or rather, that in the decomposition of muriate 31 ( 362 ) of ammonia by carbonate of lime, the process al- ways made use of, the hydrated carbonate is formed. When carbonate of ammonia, having a pungent o- dour, is exposed to the air, it loses its odour, ceas- es to redden turmeric or render blues green, and be- comes an hydrated bicarbonate of ammonia. Hence there are three carbonates of ammonia. Carbonate of ammonia, when pure, is entirely vol- atilized. If it should contain any muriate of ammo- nia, by solution in water, and the use of the tests for muriatic acid, it may be detected. After having ex- posed a-portion ofthe carbonate to heat, the residue if any, must be examined. It may contain carbon- ate of potash, or carbonate of lime, or both. The former will be indicated by an alkaline taste, and, when dissolved, affording the usual phenomena with tartaric acid, and muriate of platinum. Carbonate of lime may be proved by making a solution in ace- tic acid, noting the effervescence, and adding the tests for lime. Both these impurities are more like- ly to occur, if the carbonate be purchased in powder instead of the lump. If the alkali be saturated with nitric acid, and the usual tests added, sulphuric and muriatic salts, lime and iron, if present, may be recognisad. CARBONATED LIQUID AMMONIA. The solution of carbonate of ammonia, or carbona- ,td liquid ammonia, is usually prepared by dis- tilling muriate of ammonia and carbonate of potash ( 36o j) It is the common water of ammonia, or spirit of sal ammoniac. The preparation of ammonia, called the liquor ammonia subcarbonate, of the London Phar- macopjei?, is a solution ofthe carbonate in water, in the proportion of 4 ounces to a pint of fluid. The specific gravity of the liquor of carbonate of ammonia should be 1.150. With acids it should ef- fervesce, and when mixed with alcohol occasion a strong coagulation. This coagulation of a complete- ly saturated watery solution of carbonate of ammon- ia by alcohol, is called the offa alba Helmonta. WATER OF PURE AMMONIA The solution of pure ammonia in water, liquor am- monia, caustic ammonia, ammonia fluor, cy-c. is pre- pared by distilling muriate of ammonia and quick- lime, or by saturating water with ammoniacal gas as it proceeds from the same mixture. As this water of ammonia should be nothing more than a combina- tion of pure ammonia and water, the presence of the least portion of carbonic acid, for instance, would de- stroy a part of its strength or pungency, and of course, lessen the quantity of real uncombined alkali. The water should be fully saturated with the gas. To determine the presence of carbonic acid, we need only add a portion of muriate of lime, which is not decomposed by pure ammonia. If a precipita- tion takes place, it will indicate its existence, as a carbonate of lime will be formed. The presence of saline matter may be detected by saturating the alka- ( 364 ) li with nitric acid, and applying the tests for muriatic and sulphuric salts. The specific gravity of the pure water of ammonia shonld be as 905 to 1000 at 60 deg. Faht. A saturated solution is 0.875, wat- er being 1000. Water at 50 degrees absorbs 670 times its volume of ammonia. Jn considering the preceding preparations, viz, carbonate of ammonia, carbonated liquid ammonia, and water of pure ammonia, we perceive some im- portant differences. Carbonate of ammonia of the shops, or volatile salt of ammonia, vulgarly called smelling salts, is prepared by subliming a mixture of about equal parts of muriate of ammonia, and carbo- nate of lime ; in which we fcrm, by double decom- position, carbonate of ammonia and muriate of lime ; the first sublimes, and the last remains at the bottom ofthe sublimer. When, however, a mixture of mu- riate of ammonia, carbonate of potash, and water are distilled, muriate of potash and carbonate of am- monia are formed; and the latter will be held in so- lution with any free ammoniacal gas : but if, in the place of carbonate of potash, we use quicklime or caustic alkali, or receive pure ammoniacal gas in water, the water of pure ammonia will be the pro- duct. As muriate of ammonia is thus decomposed by potash and quicklime, and the ammonia disengaged either combined with carbonic acid, if the carbon- ate of potash be used, or in a free state; an extem- poraneous smelling bottle, equally pungent with the concrete volatile alkali.(earbonate of ammonia,) may ( 365 ) be prepared by simply mixing these substances to- gether, and introducing them into a phial. We men- tion this fact although it may have occurred to you, to show, that if the pungency of the alkali be all that is required, to stimulate the olfactory nerves, and no carbonate of ammonia, or liquid ammonia at hand, sal ammoniac may be advantageously substi nited. ai* li^CTYU^ YI. VITRATE OF AMMONIA. titrate of ammonia, a salt formed by saturating diluted nitric acid with carbonate of ammonia, and evaporating the fluid, should be free from muriatic and sulphuric acid, and, therefore, neither contain muriate nor sulphate of ammonia. It is this salt which is used for the preparation of nitrous oxyde, or protoxyde of azote, called also the exhilerating gas. When purchased in the state of salt, for the purpose of experiment, it would be as well to exa- mine it before using it. Solution in water, and the addition of nitrate of barytes and nitrate of silver, to se- parate portions ofthe solution,will be sufficient for that purpose. The nitric acid should be completely sat- urated, which may be known by the taste, and the use of litmus paper. Nitrate of ammonia contains a variable quantity of water in its crystals. It ought to be decomposed entirely at 500 deg. furnishing by >ts decomposition water, and nitrous oxyde. Should there be any residue after the action of heat, it may be regarded as an impurity, and proba- ( 368 ) bly a fixed salt, the nature of which may be known by experiment. SPIRIT OF HARTSHORN. Spirit of hartshorn is a fluid containing variable quantities of carbonate of ammonia (or Sal. C. C.) in solution, impregnated with Dippel's animal oil. It is frequently mixed with the carbonated water of am- monia, and often with the aqua ammonia puree, not only to increase its pungency, but to enable it to bear dilution with water. This fraud is rather difficult of detection. With the spirit of hartshorn alcohol occasions a very copious coagulation, owing to the presence of carbonate of ammonia; but if, on adding the alcohol, no considerable coagulation ensues, an experiment which ought to be made by way of com- parison with some genuine spirit of hartshorn, the sophistication is proved. Spirit of hartshorn should have the specific gravity of 1.500. The addition of acids which has been recommended to detect the presence ofthe pure water of ammonia, or rather the non existence of carbonate of ammonia, by not pro- ducing an effervescence, is altogether falacious; for, although the spirit of hartshorn may contain the pure water of ammonia, yet the carbonate is always pre- sent, and of course would effervesce. Spirit of hartshorn, although originally prepared from the horn of the hart, is now furnished by the dis- tillation of bones. Bones consist essentially of gela- tin and phosphate of lime, and when charred furnish ( 369 ; bone black, or, when burnt, bone ash; but when sub- mitted to destructive distillation, they are also de- composed, and furnish other products arising from a new arrangement of elementary principles. Thus it is, that we obtain an impure volatile alkali, con- taminated with animal oil, more or less empyreumat- ic, and a considerable quantity of the salt of harts- horn, now called carbonate of ammonia. The li- quor first obtained is redistilled before it is fit for use. It is more economical, and the ammonia ob- tained much purer, by distilling muriate of ammonia with quick lime, or potash. The product is then cither the water of pure ammonia, or the carbonated water of ammonia. The only possible difference is, that in the spirit of hartshorn there is a portion of Dippel's animal oil, one of the products of the distil- lation of bone. Spirit of hartshorn is now econom- ically made, at the same time that bone is carboniz- ed in iron cylinder?. ACETATE OF AMMONIA. The acetate of ammonia, or the spirit of minder- erus, should be prepared by saturating distilled vine- gar with carbonate of ammonia. When prepared with coloured vinegar, as for instance the cider vin- egar, the fluid is of a very dark colour. The vine- gar as well as the distilled, should be free from fo- reign acids, and the ammonia from foreign alkali.— This fact may be learned by employing the necessa- ry reagents. ( 370 j SULPHATE OF LIME. Sulphate of lime is a mineral, whieh occurs abun- dantly either crystallized, foliated, or compact. Se- lenite, or the foliated subspecies, presents some va- rieties, as the massive and acicular : gypsum includes all those varieties having a granular or fibrous struct- ure, whose texture is compact and earthy; and plas- ter-stone, or plaster of paris is a subspecies which is found near Paris, at Montmartre. Sulphate of lime often occurs in spring water, to which its hardness is generally attributed. See Wa- ter. It will be recollected, that some calcareous stones. as the carbonates, comprehending lime-stones, chalks, marble, stalactites, pearl-spars, marls, testa- ceous tufas, &c. are soluble in nitric and muriatic acid, and are recognised by their effervescence, and the solution producing an insoluble precipitate, (ox alate of lime,) with oxalate of ammonia ; but the com- bination of lime with sulphuric acid, if pure, neither effervesces, nor is soluble in acids. The examina- tion of gypsum, or compounds of sulphuric acid and lime, is usually effected by boiling one part with four times its weight of carbonate of potash, in a sufficient quantity of water, and separating the in- soluble mass, which now consists of carbonic acid and lime. This mass is then to be dissolved in dilut- ed nitric acid, and the nitrate of lime evaporated to dryness, and its weight ascertained. On this nitrate more than half its weight of strong sulphuric acid i? ( 371 ) to be poured, and heat applied till all the fumes (ni- tric acid vapour,) cease to appear. To the dry sul- phate, thus obtained, add twice its weight of cold water, filter off the fluid, and expose the residue to a dull red heat. The quantity of lime may be esti- mated, by deducting from the weight of the insolu- ble mass 59 parts. The nitrate of lime may be ex- posed to a red heat for some hours, when it will be converted into quick lime. Plaster-stone, properly so called, is preferred as a cement, owing to the presence of carbonate of lime, which amounts to about 17 per cent.; and, in fact, :o make a good cement with calcined sulphate of lime, a certain quantity of quick lime must be add- ed. Plaster-stone differs from the gypsums in that respect, and hence it slightly effervesces with acids. Sulphate offline is used for various purposes:— when ground, and strewed over land, it facilitates ve- getation, and is, therefore, extensively used by farm- ers : when granular, pure, and compact, it is used in the imitative and ornamental arts by the name of al- ibaster; which, however, is not to be confounded with common calcareous alabaster ; but works made if it, as busts, statues, he. are less durable and less valuable than marble : when exposed to the action of heat, the water, which is generally from 18 to 22 percent, is dissipated, and calcined gypsum or plas- ter i? obtained. The water of crystallization, or which constitutes a component part of gypsum, ex- ists invariably in the varieties we have mentioned; ( 372 j but in the anhydrous sulphate, there is a total ab- sence of water of crystallization. Calcined gypsum recovers it original hardness when mixed with water: hence its use in casting statues and busts in moulds, for stucco and various other ornamental work, and for taking impressions of medals and coins. The finer kinds of sulphate of lime, as selenite, furnishes the best plaster; it is usually mixed with gum water, after being pulveris- ed ; but for coarser work this is not indispensible. Stucco may be coloured, by previously mixing with the plaster and water different pigments. Sulphate of lime, when calcined, should be kept from the air, as it absorbs moisture, and is thereby injured; indeed the time required for fixing it, when used, is only a few minutes, and the operator is ob- liged to be expeditious. The calcination of gyp- sum may be readily performed in a common iron pot placed over a fire. In selecting the gypsum, it should be as free from colour as possible ; for some, it is known, contains va- riable quantities of oxyde of iron, which cannot fail to injure the whiteness. In the calcination of plaster-stone, as it contains carbonate of lime, il is obvious quicklime is also pro- duced: when this kind of plaster solidifies, the wa- ter not only unites with the sulphate of lime, but al- so with the lime, forming a hydrate of lime, which, like a similar compound in mortar, gradually absorbs carbonic acid. The stucco work, nevertheless, is not impaired, although the presence of quicklime is ^ 363 j better adapted when the plaster is employed asact- ment. Free caloric is given out during the combin« tion of the water. If sulphate of lime should effervesce, an indica- tion of carbonic acid, we may generally infer the pre- sence of carbonate of lime. Its quantity may be known by weighing a given, portion, and digesting it in muriatic acid, which will dissolve the carbonate of lime, and ascertaining the amount of residue and deducting it from the original weight; or the lime may be thrown down from ihe muriatic acid by car- bonate of potash, and the carbonate of lime exposed to the action of heat, and the quicklime weighed. ACETATE OF LIME.* Acetate of lime may be prepared by saturating common vinegar with lime, but is generally made by saturating the vinegar formed during the distillation of wood, and which, in that case, contains more or less empyreumatic oil. Should it contain the latter, it may be known both by its smell and taste. When *The salts of lime, for the greater part, are insoluble in wa- ter ; and some, which are soluble, cannot be crystallized.— When a salt of lime is insoluble, it is necessary to decompose it, by boiling it with a solution of carbonate of potash. The solu- ble salts remain uncharged with pure ammonia, but are pre- cipitated by potash or soda. Oxalate of ammonia occasions a white precipitate. Citrate or tartrate of ammonia has the same effect, but not so immediately. They are not precipitated by ferrocyanate of potash ; but infusion of nut galls affects some of them. 32 ( 374 ) gently torrefied this smell is said to be removed.— The salt, if then decomposed by sulphuric acid in distillation, will furnish a colourless and grateful vin- egar. When acetate of lime is mixed with a solu- tion of alum, an acetate of alumina will be formed, -and remain in solution. The acetate of lime should be entirely free from iron. The presence of this metal may be shown by tincture of galls, and by ferrocyanate of potash. Acetate of lime when mix- ed with sulphate of soda, will produce sulphate of lime and acetate of soda. The latter may be separ- ted from the sulphate of lime by filtration, and de« composed by sulphuric acid. ACETATE OF ALUMINA. Acetate of alumina, a preparation used very ex- tensively by the calico printers as a mordant, is pre- pared by decomposing the acetate of lime, or acetate of lead, by a solution of alum. Sulphate of lead is precipitated in the latter instance, and sulphate of lime in the former. It is of importance that this salt should be pure, and free as well from iron, as from lime and magnesia. The detection of these sub- stances may be severally effected by using the tine-* ture of galls, oxalate of ammonia, and carbonate of anxmonia, with phosphate of soda. 375 ) ACETATE OF IRON.* The acetate of iron is a salt much used in dyeing. There are two salts of this kind ; the proto acetate ■ nd per acetate. The first is formed by digesting sulphuret of iron in acetic acid, and the second by digesting metallic iron. The calico printers and dy- ers usually prepare their iron liquor by dissolving iron in pyroligneous acid, or by mixing the solutions of acetate of lead and sulphate of iron. The iron li- quor should not contain any sulphate of iron, which may be known by adding muriate or acetate of bary- tes. Iron liquor is preferred in many operations of dyeing to any other salt of iron. ACETATE OF ZINC.f Acetate of zinc is formed either by dissolving the * The salts of iron are characterised in general by their solu- bility, the solution having a greenish or yellowish red. colour, and an astringent taste. Ferrocyanate of potash occasions a blue precipitate, or which becomes blue by exposure to the air. Aqueous sulphuretted hydrogen produces no precipitate in the proto-salts, but render the solution nearly colourless, whereas the hydrosulphuret of potpsh with all the salts of iron, occasions a black precipitate. Gallic acid, or the infusion of nut galls, produces a black or purple precipitate, at least if the solution has been for some time exposed to the air. Phosphate of soda occasions a white precipitate. Succinate of ammonia with the peroxydized salts, gives a flesh coloured precipitate, which effect is not produced with the proto salts.— Benzoate of ammonia gives a yellow precipitate with the per- salts. tTiie salts of zin<\ for the greater part, are soluble in water ( 376 ) oxyde of zinc in acetic acid, or by decomposing the sulphate of zinc with acetate of lead. The acetate of lead should be entirely decomposed, as well as the sulphate of zinc ; neither of which should exist with the acetate. Some of the acetate may be dissolved, and the solution examined for sulphuric acid, if it should contain sulphate of zinc ; and for lead, if the aceta.te of that metal should be suspected. ACETATE OF LEAD.* Acetate of lead, or sugar of lead is formed by dis- solving the white oxyde or carbonate of lead in ace- tic acid. It is sometimes called a super acetate, but the salt is neutral. When dissolved in water, and the smallest portion of carbonic acid is present, a and the solution is colourless and transparent. The effect of reagents are: ferrocyauate of potash produces a white gelatin- ous precipitate; hydrosulphuret of potash and sulphuretted hy- drogen gas, a white precipitate ; infusion of nut galls no pre- cipitate ; alkalies occasion a white precipitate soluble with ease in sulphuric or muriatic acid ; zinc is not precipitated in a me- tallic form by any of the other metals; but sulphocyanate of potash and hydriodate of potash produces, respectively, a white precipitate. *The salts of lead are recognised by some of them being so- luble, and others insoluble in water, without an excess of acid ; by their yielding very readily a button of lead before the blow pipe; by their more or less sweet taste, accompanied with some degree of astringency ; t)y the production of a white precipitate with the ferrocyanate of polish, and a black precipitate by hy- drosulphuret ot potash and aqueous sulphuretted hydrogen ; by a white precipitate with gallic acid, and the infusion of nutgalls, and by the precipitation of lead in a metallic state by a plate of zinc, forming the lead tree. See Adulteration of Wine., ( 377 ) white insoluble compound of lead falls, a little ace- tic acid is liberated, and the solution then becomes our. Water containing sulphates and muriates in solution, affect acetate of lead, by producing a tur- bidness more or less great. What is called the subacetale is the same as the Goulard's extract of lead, which is usually made by dissolving litharge in vinegar. If litharge be boiled with sugar of lead, the same compound is formed. If the acetate of lead should be adulterated with acetate of lime, or acetate of barytes, they may be detected by adding to a diluted solution oxalic acid for lime, and sulphuric acid for barytes. Acetate of lead ought to be entirely soluble in water. When distilled with sulphuric acid, it should furnish acetic acid, or radical vinegar, and sulphate of lead remain in the retort. If any other metal, besides lead, be suspected, the fact may be proved by treating it with the usual reagents. SULPHATE OF ZINC. Sulphate of zinc, or white vitriol, is obtained pure by dissolving zinc in diluted sulphuric acid. The common sort often contains iron, and is of a dirty yellow colour. The iron may be detected by tinc- ture of galls. If sulphate of zinc be dissolved in water, and li- quid ammonia added to the solution, the oxyde of e.inc and oxyde of iron will be precipitated ; but on adding an excess of ammonia, the former will be ta- ( 378 ) ken up, leaving the latter; and, if no residue be left we may then infer that the salt was free from iron, The oxyde of zinc may he separated from the am- monia by the addition of an acid. Sulphate of zinc may be easily purified by dissol- ving it in water, and putting into the solution a quan- tity of zinc filings. The zinc precipitates the for- eign metals, and takes their place. The solution is then to be filtered,, evaporated, and crystallized.— Besides iron, sulphate of zinc is often contaminated with copper and lead, which may be detected by the usual reagents. In consequence of these for- eign substances, sulphate of zinc is usually colour- ed, and, when dissolved in water, lets fall a dirty brown sediment. It is generally formed in the large way by roasting sulphuret of zinc, or blende, by which the sulphur is acidified ; then dissolved in water, and the solu- tion filtered, evaporated and crystallized. SULPHATE OF IRON. Sulphate of iron, green vitriol or copperas is a sulphate of iron, with the iron oxydized to the min- imum. It is the proto sulphate of iron, and crystal- lizes in green rhomboidal. prisms. It is usually for- med by the decomposition of pyrites, or sulphuret of iron,, and is prepared also by the solution of iron in diluted sulphuric acid. It is also found native, but the native salt is rare, and generally impure. The other salt of iron is the per sulphate, commonly c ai- led the red sulphate of iron.. ( 379 ) Copperas or sulphate of iron is manufactured if Vermont, at Strafford, from pyrites. The pyrites is found with quartz. It is broken into small frag- ments, and thrown into a heap. On applying water the decomposition commences, and so much heat is evolved, as presently to raise the temperature ofthe heap to such a degree as to char wood, boil water, sublime sulphur, &tc. Sulphurous acid gas, we are told, is disengaged in abundance. In the course of three or four weeks the whole is disintegrated, and ready to fall into the state of powder. It is then lix- ivated with water, and the solution evaporated and crystallized. The process is well described by Dr. Locke, in a communication in Silliman's Journal iii. p. 326, who remarks, that the iron pyrites con- tains some sulphuret of copper,and hence the lixivi m is impregnated with sulphate of copper, which is decomposed by suspending in the liquor some frag- ments of old iron. The copper, thus separated, the workmen call " copper mud-" Four men, it seems, manufacture 100 tons of copperas in a year, besides Attending to other employment. Some of the de- composed sulphate of iron is found native, a barrel of which it is stated, furnishes 3331bs of copperas ! Copperas was manufactured in Lancaster, Pa. du- ring the revolution, from the cubic pyrites, called in that neighbourhood Lancaster jack stones: the py- rites were first roasted, then exposed to air and lix- ivated, he. in the manner already mentioned. The process is fully detailed in Dr. Pennington's Chem- ical Essays, written in 1793. Iron pyrites occur in f 380 ) abundance in the United States, but we have heard of few establishments for the manufacture of cop- peras. It is very certain, that as the process is by no means complicated, nor expensive, and pyrites so abundant in certain parts ofthe United States, the manufacture of sulphate of iron would be advantag- eous. It is to be recollected that an extensive bed or mass of pyrites is found at Cape Sable, accompa- nying earthy lignite, from which many tons of alum have been made. See Alum. When these pyrites are exposed to the air, they gradually decompose, and combustion ensues. Sulphate of iron is scarcely ever adulterated.— Sometimes the presence of sulphate of copper is sus- pected, which may be detected by solution in wat- er, and the addition of ammonia in excess. The vitriol may be purified, and the copper completely separated by immersing a plate of iron. Metallic copper will be precipitated. RED SULPHATE OF IRON. The persulphate of iron, in which ihe red oxyde is combined with sulphuric acid, does not crystal- lize, but furnishes a deliquescent mass of a brown colour. This salt should contain none ofthe green sulphate. A mixture ofthe two salts I have imper- fectly detected,and separated, by crystallization; the red sulphate constituting the mother water. Unless the crystals are soon separated they disappear. The ( 381 ) persulphate forms the most intense colour with an in- fusion of galls ; and in that respect is preferable to the common sulphate for the preparation of ink and black dye. The red sulphate is produced in the mo- ther waters of the sulphate. The red sulphate may be formed very advantageously by treating the green sulphate with nitric acid.* * Having mentioned writing ink, it may not be amiss to add, that ordinary ink powder, from which ink is prepared by infu- sing it in vinegar and water, is merely a mixture of powdered galls, green vitriol, and gum arabic. The proportions are two ounces of galls, half an ounce of vitriol, and a drachm of gum. These proportions will make a pint or more of ink. Although the per oxyde of iron, and consequently the per salts of iron, furnish the most intensely black ink, which was formerly sup* posed to be nothing more thau a combination of gallic acid and oxyde of iron, yet it is now known, that ink also owes its black- ness to the presence of tannin, which is likewise in combina- tion ; hence, strictly speaking, writing ink is a tanno-gallate of iron. By substituting the persulphate of iron, for the common sulphate, in the same proportion, 1 have succeeded in forming a very brilliant black. The ancient writing ink, which was so indestructable, had a carbonaceous basis, and in that respect re- sembled our modern printing ink. Dr. Lewis (Phil. Com. p. 377,) made a number of valuable experiments on the forma- tion of writing ink. He found the fullest black was produced, •vhen equal weights of galls and sulphate of iron were used ; but the ink soon fades. To make it permanent the galls ought to be thrice the weight of the vitriol. The addition of logwood increases the blackness ofthe ink. The following recipe is re- commended by Dr. Lewis for making the best ink: Logwood, t ounce. Nutgalls in powder, 3 do. Green vitriol, 1 do. Water 1 to 2 quarts ( 382 ) PROTOMURIATE OF IRON. When iron filings are dissolved in muriatic acid, and air excluded, the protomuriate of iron results; and by exposure to air, or the addition of a little ni- tric acid, it is changed into the per muriate. This per mtiriate forms the basis of the tinctura ferra muriaiis ofthe London Pharmacopaeia. If sulphate of iron should be suspected in either of the muriates, owing to the use of an impure acid, it may be known The logwood and nutgalls are to be boiled together, adding more water as it evaporates; then strain the decoction, and add the vitriol, after which one to two ounces of gum arabic. In the recipe given by Brande, (Chemistry, p. 506, Am. edit.) 3 ounces of galls, and one ounce each of green vitriol, logwood shavings, and gum arabic are infused in a quart of vinegar, di- gested for several days, and strained for use. Three grains of corrosive sublimate to every pint of ink, will prevent it effectu- ally from becoming mouldy ; more so, in fact, than cloves. The colour of writing ink is apt to fade by age. It may be restored by washing the writing with an infusion of galls. Acids destroy ink ; but to prevent, in a measure, this effect, and oth- erwise improve ink, Mr. Brande recommends the addition of an ounce of Indian ink to the above quantity of materials. , • Accum (Chem. Amus. p. 251,) observes, "that we have at present no ink of a similar kind, equal in durability and colour, to that used in former times, as will at once become obvious bv an inspection of many ofthe MSS. written in England in the time of the Saxons." Mr. Close, (Nich. Journ.% vo. ii. 145,; however, hasproposed an indelible writing ink made by dissol- ving with the assistance of heat, 25 grains of gum copal in pow- der in 200 grains of oil of lavender, and mixing this solution with 2 1-2 to 3 grains of very fine lamp-black. This composi- tion is particularly useful for writing the labels of boutes. ( 383 ) by diluting it with water, and adding thereto muriate of barytes. MARTIAL FLOWERS. The floresmartiales, or the present^rrum ammom- ntum ofthe Pharmacopaeia, which is prepared by sub- liming a mixture of muriate of ammonia and per ox- yde of iron, may be examined for copper, if there is reason to suspect the presence of that metal. This preparation of iron consists chiefly of muriate of am- monia and per muriate of iron. NATIVE PRUSSIAN BLUE. The mineral called native Prussian blue, which sometimes occurs in the form of a blue earthy pow- der, is the same as the protophosphate of iron, and is employed occasionally as a pigment. The colour maybe weakened by sundry additions; the presence of which is shown by experiment. The proportion of phosphoric acid may be learned by dissolving the mineral in nitric acid, and adding acetate of lead, which will form a phosphate of lead, and from the weight of the phosphate the quantity of phosphoric is acid determined. The iron may be separated from the nitric acid by ferrocyanate of potash, he. The native blue phosphate of iron, blue iron earth, or native Prussian blue, is impure ; containing more ( 384 ) or less alumina, and some silica. When first taken out of the earth, as in the locality in New-Jersey, an account of which I published in Bruce's Mineralo- gical Journal, it has an argillaceous feel, and a milky appearance; but, by a short exposure to the air, be- comes blue, owing, in all probability, to the absorp- tion of oxygen. It is then dry, and the pieces when broken represent a uniformity of colour, and, in some instances, are remarkably friable, crumbling to pie-1 ces between the fingers. In this state, however, it is easily ground, and mixed with oil. The alumina, doubtless, makes a good basis for the phosphate of iron, in the same manner as in the Prussian blue of commerce. If pulverised very fine, and mixed with gum, or size, it will form a very good water colour; not equal, however, to the perferrocyanate of iron, which is the blue pigment usually employed for that purpose. For an account of Blue Pigments, see a preceding lecture. MURIATE OF GOLD. Muriate of gold, a salt lately introduced in medi- cine in syphilitic diseases, but without any decided advantages, is prepared by dissolving/gold in nitro muriatic acid, and evaporating the solution. The, muriate, if pure, should be wholly soluble in water ; decomposed by phosphorous and eharcoal; precipi- tated in the state of purple powder of Cassius by pro- tomuriate of tin; and the gold obtained in its metal- lic state by the protosulphate of iron. It should also ( 385 ) be entirely decomposed by aether, forming an atht- rial solution of gold* NITRATE OF SILVER.f Nitrate of silver or lunar caustic is readily formed by dissolving silver in nitric acid. It may be ob- served, that if the nitric acid contains the muriatic, muriate of silver will be produced, and render the solution turbid. If the silver contains copper, the so- lution will have a greenish hue ; and if it contained gold, it will remain undissolved in the form of a black powder. Nitrate of copper is frequently found in this salt, ■ '—■■■ — ■ ■—i---------- *When sulphuric aether is mixed with a solution of muriate of gold, the aether reduces the gold, which remains in solution forming the stherial solution, and the muriatic acid thus separ- ated forms a distinct fluid containing very little gold. This so- lution of gold is used as an easy method of gilding steel. When highly polished steel is immersed in it, a coat of gold is formed upon it, and the aether evaporates. By means of a brush, fig- ures may be deliniated on polished steel instruments, as on ra- zors, scissors, pen knives, fcc. In this way, the points of thumb lancets may be preserved from rust. The steel should be immersed into water the moment it has been gilt. f The salts of silver are readily reduced before the blow pipe on charcoal. A plate of copper precipitates the silver in a me- tallic state, so does also a solution of sulphate of iron. Ferro- cyanate of potash occasions a white precipitate; hydrosulphur- et of potash a black; muriatic acid and alkaline muriates a white precipitate resembling curd; and gallic acid, and infusion of nut galls, a yellowish brown precipitate, in most of the solu- tions of silver. 33 ( 386 ) either derived from impure silver, or intentionally added. Copper is detected by dissolving the salt in pure water, and adding to the solution an excess of pure ammonia. The watery solution of lunar caustic, occasions, with muriate of soda, a copious precipitate resem- bling curd. The whole ofthe silver is separated from the ni- trate, by immersing a plate of copper, and nitrate of copper is produced.* TARTRATE OF POTASH-AND-ANTI- MONY. The tartar emetic, tartarized antimony, or antimo* niated tartrate of potash, but more properly the tar- trate of potash-and-antimony, is a triple salt formed by saturating the bitartrate of potash with oxyde of antimony. Tartar emetic should crystallize in an octahedral and tartrahedral form. It is decomposed by the al- *In consequence ofthe solubility of silver in a preparation of sulphuric acid, made by dissolving one pound of nitre in eight or ten p junds of sulphuric acid, this compound has been economically employed for recovering silver from old, plated goods. It is said to dissolve about one fifth of its weight of sil- ver, but does not act upon copper, lead, or iron. The acid should be kept at a temperature of between 100 deg. and 200 deg. Fah't. and the plated copper added in small pieces, fre- quently stirring the acid. The silver is separated by muriate of soda, and the muriate of silver, thus formed, reduced by fusion with carbonate of soda. ( 387 ) kalies^ by sulphuretted hydrogen and hydrosulphur et of ammonia, which produce orange coloured pre- cipitates ; and by bitter and astringent vegetable in- fusions, but they do not render it inactive as a med- icine. It will be sufficient, however, to add, that with acetaie of lead it should produce a precipitate completely soluble in dilute nitric acid, and with sulphuret of ammonia a gold coloured sulphuret of antimony. The tartar emetic, which is sold in a pulverised state, may contain both sulphate and tartrate of pot- ash. In that case, with regard to the sulphate, so- lution in water, and the addition of muriate of bary^ tes, and insolubility of the precipitate ip muriatic acid, will determine the fact. The presence of iron, copper, he. may be readily detected by the usual reagents. If sulphate of zinc, or white vitriol, be suspected, the zinc may be rendered manifest by first adding ammonia, which will precipitate the pro- toxyde of antimony, along with the oxyde of zinc, as well as some other metals, if present. If we con- tinue to add ammonia as long as any thing is taken up, the residue will consist of oxyde of antimony, he. and may, if required, be examined. The am- moniacal solution, if it contains oxyde of zinc, will occasion a precipitate if nitric or muriatic acid be gently added ; or, by evaporation, the oxyde of zinc will be deposited. The protoxyde of antimony is fusible and volatile at a red heat. When tartar emetic is dissolved in water, it may ( 388 ) be well to observe, that the acids, as sulphuric, nitric, and muriatic, poured into it, precipitate a bitartrate of potash. When tartar emetic is exposed to a red heat, it first blackens, and afterwards leaves a resi- dum of metallic antimony and subcarbonate of pot- ash. " From this Phenomena," says Dr. Ure, in his edition of Nicholson's Chemical Dictionary, " and the dfeep brownish red precipitatev by hydrosulphur- ets, this antimonial combination may readily be re- cognised." The precipitate, if dried on a filter, and heated with black flux, will give a globule of metal- lic antimony. Galls, in the form of infusion, are said to be an ac- tive precipitant of tartar emetic. It is said to sepa- rate only an oxyde of the metal. When a plate of iron or zinc is plunged into antimonial solutions, a black powder precipitates in great abundance. Tartar emetic has been employed in the fabrica- tion of spurious ipecacuanha; which is either put to the common ipecacuanha to increase its strength, es- pecially if old, or added in certain quantities to pul- verised roots, which resemble the ipecac. The fraud may be discovered by infusing the suspected ipecac- uanha in water, which will take up the tartar emetic, and by the use of reagents. Although tartar emetic may be purchased in a crys- tallized state, yet the fact is well known, that the crystallized salt is not uniform in its constitution.— It is, therefore, always advisable to pulverise it, if bought in that state, before using it, ( 380 ) MURIATE OF ANTIMONY.* When the oxyde of antimony is combined with muriatic acid, a muriate of antimony is formed, which was formerly called the butter of antimony. The particular character of this salt is, that when mixed with water it is decomposed, and forms a white pre- cipitate, formerly known by the name of Algoroth's powder, and considered by some a submuriate, and by Brande as a hydrated protoxyde of antimony.— The muriate of antimony is a deliquescent salt, and is a powerful caustic. The precipitate obtained by water, has been used for the preparation of tartar emetic. Iron may be detected as before mentioned. VITRIFIED SULPHURETTED OXYDE OF ANTIMONY. The glass of antimony, or vitrified sulphuretted oxyde of antimony, is very liable to adulteration, and particularly with the glass of lead ; a fraud which * The salts of antimony have the following distinguishing properties: Their solutions are usually brown, and are fre- quently decomposed during solution in water, a white preciPi" Jate being formed. Ferrocyanate of potash occasions a white precipitate, which is merely an oxyde of the metal. When concentrated, no pre- cipitation takes place. Hydrosulphuret of potash produces an orange coloured precipitate. Gallic acid occasions a white pre- cipitate, which is merely, in the opinion of some, the oxyde of the metal separated by the water of the gallic acid. A plate of tton or zinc precipitates a black powder. See the detection of Antimony. 33* ( 390 ) was largely practised upon the London druggists.— It was imported from Germany and Holland. This adulteration is easily detected by dissolving the fine- ly powdered glass in hot nitric acid, diluting the so- lution and filtering it. If the filtered liquor be now mixed with a solution of sulphate of soda, a white precipitate of sulphate of lead, if lead were present, will be obtained. Mr. Luke Howard, who paid much attention to this adulteration, as appears from his observations in the Philosophical Magazine, xxxv. 236, in sub- stance, that glass of antimony has a rich brown or reddish colour, with the usual transparency of glass; that the glass of lead is duller, much less transparent, and even sometimes opaque; that the specific grav- ity ofthe true never exceeds 4.95, while that ofthe spurious is 6.95, or comparatively as 5 to 7 ; that the true dissolves with an hepatic smell in muriatic acid, and the solution is turbid without a sediment, where- as the spurious turns the acid yellow, giving out the odour of chlorine, and leaving much sediment; that when a little of each solution is dropped separately into water, the true deposites oxyde of antimony in a copious white coagulum, and is likewise precipitat- ed by sulphuret of ammonia of an orange hue, while the spurious gives no precipitate in water, neither does it give an orange precipitate, but affords one of a brownish black; that the spurious produces with acetic acid a sweetish salt, having the properties of acetate of lead; and that even a very small mixture ofthe spurious may be known by itedeLasiu^, more ( 391 ) or less, the bright orange colour of the precipitate occasioned by sulphuret of ammonia. CROCUS OF ANTIMONY. When the protoxyde of antimony is combined with larger quantities of the sulphuret, the compound called the crocus of antimony, liver of antimony, fyc. is produced. This preparation is largely employed in the manufacture of tartar emetic. Should it be sophisticated with red lead, the fraud may be detected by dissolving it in acetic acid, fil- tering the solution, and adding a solution of sulphate of soda, which will throw down a white precipitate. Sulphuretted hydrogen, while it produces with an- timony an orange coloured precipitate, forms with lead a precipitate more or less black. PRECIPITATED SULPHURETTED OX- YDES OF ANTIMONY. Kerme's mineral, the golden sulphur of antimony, and the precipitated sulphur of antimony, are prepar- ations of the same mineral. They are made either by dissolving the alkaline sulphuret of antimony in water with heat, and allowing the kermes to precipi- tate as the fluid cools ; or by adding to the antimo- niated alkaline sulphuret, even after the separation ofthe kermes, dilute sulphuric acid, which produces a precipitate ofa golden colour. A hydrosulphuret- f.ed oxyde is produced in the first instance, and a ( 392 ) sulphuretted hydrosulphuret in the second. When the acid is added, it will be sufficient to observe, that the sulphur falls in combination with the kerrne's that remains in solution, and sulphate of potash is al- so produced. The precipitates should be well wash- ed ; the former, to separate any alkaline sulphuret that may be attached to it, and the latter, to wash off the sulphate of potash. Kerme's mineral and golden sulphur of antimony, should neither have an alkaline, nor acid taste.— With the microcosmic salt and with borax, before the blow pipe, they should form a hyacinth coloured glass, and emit at the same time a sulphurous or he- patic odour. They ought to be soluble in tartaric acid, as well as in nitric acid, and the solution give with the alkalies a white precipitate. The kerme's mineral, the most expensive of the two, is ofa dark brown colour, and is readily known from the precip- itated sulphur of antimony. When the black sul- phuret of antimony (antimony of the shops,) is treat- ed with a diluted acid, for the purpose of forming pure sulphuretted hydrogen gas, there remains in the retort or gas-bottle a large quantity of the golden sul- phur of antimony, formed in consequence of the un- ion of the hydrosuJphuretted oxyde with sulphur. PHOSPHATE OF LIME AND ANTIMONY. The antimonial powdery or James' powder, is a phosphate of lime-and-antimony, prepared at pres- ent by dissolving the phosphate of lime and protox- ( 393 ) yde of antimony in muriatic acid, and precipitating them by ammonia. This mode of preparation ren- ders the compound more uniform in its composition; and effects. The old process Consisted in calcining hartshorn with sulphuret of antimony, and pulver- ising the phosphate, which was more or less a me- chanical mixture. James' powder has little or no taste, and is insolu- ble in water. If mixed with tartar emetic, that salt may be detected by solution in water, filtering the solution, and adding the tests already mentioned. If it contain chalk, it will effervesce. Muriatic acid will dissolve antimonial powder without decom- position, a mean of ascertaining its purity, which will again be precipitated by ammonia. Phosphate of lime is of itself soluble in muriatic acid; hence, by digesting common bone in that acid the gelatin and alluminous matter will be left, retaining the shape of the bone, while the phosphate of lime will be dis- solved. The addition of ammonia will throw down the phosphate. Hence Mr. Chenevix took advantage of this fact, for the preparing antimonial powder, by making a compound solution of the prot oxyde of antimony and phosphate of lime, and precipitating them together. SULPHATE OF MAGNESIA.* Sulphate of magnesia, or Epsom salt is found in * Trfe salts of magnesia, for the greater part, are very soluble. ( 394 ) mineral springs, as the springs of Epsom, and in s0a water; and is frequently made by calcining certain minerals which contain magnesia and sulphur, or sul- phuret of iron. It is from this salt that the magne- sia alba of the shops is prepared. Epsom salt as it occurs in commerce is often de- liquescent, a property which it possesses in conse- quence ofthe admixture of muriate of lime and mu- riate of magnesia, which are known to absorb mois- ture, and run per deliquium. If a solution of this salt in water be made, we may detect the presence of muriatic acid by the addition of sulphate of silver; and of lime, by using either oxalate of ammonia, or bicarbonate of ammonia, which does not precipitate magnesia. Or we may proceed with the solution as follows : add nitrate of barytes until all the sulphuric acid is separated, then filter the solution and add nitrate of silver. The latter will precipitate the muriatic acid, in combina- tion with the silver. If some sulphuric acid be pour- ed on sulphate of magnesia, containing the muriate aforementioned, muriatic or hydrochloric acid gas will be apparent, not only known by its peculiar and capable of crystallizing. They are decomposed by the al- kalies, and carbonated alkalies, but not by sulphate of soda, which, more properly, does not occasion any precipitate. Phos- phate of soda produces no effect; if, however, ammonia be add- ed a white precipitate then falls, consisting of phosphoric acid, ammonia, and magnesia. Ferrocyanate of potash occasions no precipitate in a salt of magnesia, unless the acid has a metallic base ( 395 ) smell, but by white clouds when a stopper moisten ed with ammonia is presented to it. Muriate pf soda is not unfrequently found in abundance, mixed with the sulphate of magnesia.— The salt in that state, is not deliquescent. It will, however, occasion a precipitate with sulphate of sil- ver. There is another salt, which has been discovered in Epsom salt; it is the triple sulphate of magnesia- and-potash. It is sparingly soluble, is less bitter than sulphate of magnesia, and occasions a grittiness in the mouth. But the salt, with which the Epsom is most likely to be adulterated, is sulphate of soda. Even this salt may be made to resemble the magne- sian salt in appearance, by briskly agitating it at the moment when it commences to crystallize. If the Epsoin consist ivholly of Glauber's salt, thus irregu- larly crystallized, the fact may be known by adding carbonate of potash, which, of course, will produce no precipitation. " If only a part should consist of sulphate of soda, the solution may be mixed with pure ammonia, and heat applied ; then separate the precipitate, consisting ofthe magnesia, by filtration ; evaporate the fluid to dryness, and expose the mass to such a heat as will volatilize the sulphate of ammo- nia, when that of the soda will remain fixed. Ten grains ofthe dried crystals, or effloresced salt, indi- cate about twenty-two and a half of crystals. It is known that about 57 parts of subcarbonate of potash will decompose 100 parts of crystallized sul- phate of magnesia, and afford between 35 and 36 of ( 396 ) the dry carbonate. If the salt, therefore, give a les* proportion of carbonate of magnesia than here stated, we may safely infer the presence of sulphate of soda. Oxalic acid has been used by mistake for Epsom salt. Its acid taste, and precipitation of lime water will detect it. . ACID OF BENZOIN. Acid of Benzoin, commonly called flowers of Benzoin, is obtained from the socalledgwm benzoin, of the *hops, by sublimation, by boiling the benzoin with quicklime, and decomposing the benzoate of lime with muriatic acid. This acid is soluble in 30 parts of boiling water, and very sparingly in cold wa- ter. It should have a white colour, and peculiarly grateful smell. When in the least oily ithas a dark colour; and, if burnt in the sublimation, an empy- reumatic flavour. Benzoin acid may be purified by solution, filtration, and crystallization. It is solu- ble in alcohol. When exposed to heat, it ought to evaporate. Any residue may be regarded as an im- purity, which may be examined by the usual rea- gents. ACETIC ACID. Acetic acid or radical vinegar, formed either by distilling the metallic acetates perse, or with sulphur- ic acid, is often contaminated by sulphurous and sul- phuric acid. The first gives an unpleasant sensa- ( 397 ) tion,and peculiar smell, which ceases if some bkick oxyde of manganese be put into it. Sulphuric acid is known by the barytic test; copper, by ammonia, and lead, by the hydrosulphurets. Its specific gra- vity should be 1. 066. See Vinegar. TARTARIC ACID. This acid, called also the acid of tartar, is often sophisticated with the bisulphate of potash. It is obtained from cream of tartar by dissolving it in wa- ter, and saturating the excess of acid with carbonate of lime; a tartrate of lime is formed, which is de- composed by sulphuric acid ; the sulphate of lime is then separated by filtration, and the tartaric acid remains in a fluid state, which may be evaporated and crystallized. As only the excess of acid in cream of tartar is separated by this process, we may obtain the whole of the acid in the remaining tar- trate of potash by adding muriate of lime, and treat- ing the tartrate of lime as before ; or, instead of us- ing carbonate of lime in the first instance, we may employ altogether muriate of lime, and the products would be muriate of potash and tartrate of lime. Tartaric acid, we remarked when treating ofwine, exists in the grape in combination with potash ; and when the must is fermented, is deposited usually with colouring matter in the form of red tartar. This red tartar is also deposited from wine in wine casks. When redissolved, filtered, evaporated, and crystal- lized, it then forms the white tartar, or crystals of 34 ( 398 ) tartar, which in a pulverised state is our cream of tartar. The bitartrate of potash exists, however, in a greater or less degree in wine; and very frequent- ly the acescency of wine is owing to another acid, the acetic, generated by the acetous fermentation.— See p. 34. In consequence of the combination of tartaric acid with lime, and the insolubility ofthe compound, the Greeks and Romans, without knowing its action, us- ed lime or calcined oyster shells to correct the acid- ity of this wine; a practice still preserved with our modern wine merchants. The use of lead in cor- recting the acesency, was also known ; but the solu- bility of the lead in wine does not depend on the tar- taric acid, although it separates it from the fluid, as the tartrate of lead is insoluble, but on the presence of other acids, as the acetic : sugar of lead when ad- ded to sour wine, containing tartaric acid, forms a tartrate of lead ; but lead thrown into wine, the acid- ity of which is owing as well to acetic as to tartaric acid, will be soon corroded, and tartrate and acetate of lead formed; the latter, if all the tartaric acid be faken up, will remain in solution. With respect to the presence of sulphuric acid in tartaric acid it may be shown hy dissolving the acid in water, and adding acetate of lead. If an insoluble precipitate should be formed, the presence of sulphuric or muriatic a- cid, or of both is inferred. A precipitate of tartrate of lead is always produc- ed, but is known from the sulphate or muriate of lead by its entire solubility in pure nitric or acetic ( 399 ) acid. The precipitate occasioned by the muriate of barytes, should be insoluble in muriatic acid, if sulphuric acid had been the cause of the precipita- tion. Tartaric acid when added to solutions of potash, unites with the alkali, and gradually precipitates in the form of bitartrate of potash. BORACIC ACID. Boracic acid, or sedative salt of Homberg, is ob- tained from borax by solution in hot water, and the addition of sulphuric acid. The crystals of pure bo- racic acid are in small hexangular scales, which are totally dissolved in five times their weight of alcohol. This solution when set on fire should emit a green flame. It has no smell; but, when sulphuric acid is poured on it, a transient odour of musk is produced, Borax is a salt composed of this acid united with soda. SUCCINIC ACID. Succinic acid, or acid of amber, is prepared by the distillation, or sublimation of amber. It is puri- fied by forming it into a succinate of lead, and de- composing the succinate by sulphuric acid. The ordinary process is to dissolve it in water, and crys- tallize repeatedly. In the former case, nitrate or muriate of barytes will show whether any sulphurit acid remains mixed with the succinic solution; and ( 400 ) if so, it may be withdrawn by digesting the liquid with a little more succinate of lead. If tartaric acid be suspected, it may be known by adding cautious- ly to the solution of acid in water, carbonate of pot- ash, which forms a very difficult soluble bitartrate. If muriate of ammonia be present, nitrate of silver will discover the muriatic acid, and a solution of pure pot- ash the ammonia, by producing the odour of ammonia. And if the acid of amber is soluble in twenty-four parts of cold, or eight of hot water, and is volatiliz- ed on a red hot iron without leaving any residue its purity may be inferred. SULPHURIC ACID. Sulphuric acid, vitriolic acid and oil of vitriol, is an acid formed by the combustion of sulphur. Sulphuric acid was originally prepared by the distillation of green vitriol. It is now formed by the combustion of sulphur with nitre in leaden chambers, at the bottom of which is placed a quantity of water, in order to unite with, and condense the sulphuric acid. By the combustion of sulphur, in contact with nitrate of potash, sulphurous acid gas is gener- ated, as a part ofthe oxygen of the nitric acid is thus taken up. The nitric acid is, therefore, decomposed and furnishes also a given quantity of deut oxyde of azote, or nitrous gas. That it is not the nitrous acid vapour, which is disengaged, is evident from the subsequent effect. We have then in the chamber sulphurous acid gas, nitrous gas, and atmospheric air, composed of oxygen and azote. The moment ( 401 } me nitrous gas comes in contact with the atmosphe- ric air, it seizes its oxygen and forms nitrous acid, which then exists in the state of vapour. The sul- phurous acid now decomposes the nitrous acid, in which the water facilitates the decomposition; and while it reduces the nitrous acid to its original state, that of nitrous gas, it is converted into sulphuric a- cid. When more air is admitted into the chamber, the same gas is again converted into nitrous acid, which is again decomposed, and thus every new ac- cesion of sulphurous acid produces more sulphuric acid. The materials are renewed from time to time, until the water in the chamber becomes sufficiently saturated with the acid: The diluted acid is then gently evaporated until the acid is sufficiently con- centrated ; and, to make it perfectly pure, is distilled in glass retorts. The specific gravity of sulphuric acid should be 1/848 at 60 deg. Faht. - When of a greater density there is reason to suspect the presence of sulphate of lead When diluted with water, it should remain transparent; if not, and a sediment is formed, the presence of sulphate of lead may be referred. If iron or copper be suspected, saturate a portion ofthe diluted acid with pure carbonate of soda, and add to a portion of it the ferrocyanate of potash, and to another, tincture of galls; the former will strike a blue, and the latter a black colour. To another por- tion add ammonia ; this will detect copper by form- ing a blue colour. If lead be suspected, (the great- 34* ( 402 ) er part of which, however, will have been precipita- ted on the addition of the water,) add the usual rea- gents for that metal, as the hydrosulphurets. If sulphate of potash be present, the acid must be saturated with ammonia, and the whole evaporated to dryness, and the dry mass then exposed to heat. which will volatilize the sulphate of ammonia, and leave the sulphate of soda or of potash. The resi- due, dissolved and examined, will indicate one or the other, or both. After saturating with ammonia, mu- riate of platinum will show the presence of potash by producing a precipitate. The sulphate of lead may be collected, and reduced on charcoal by the blow pipe. SULPHUROUS ACID. Sulphurous acid, or aqueous sulphurous acid, is water saturated with sulphurous acid gas. Water thus impregnated, is often used in bleaching; the effect of which may be shown with the infusion of litmus, and of red roses. The sulphurous smell ceases a short time after the addition of the black oxyde of manganese. Should the sulphurous acid be contaminated with sulphuric or other acid, it would redden, instead of destroying the colour ofthe infusion of litmus. NITRIC ACID. Nitric acid is frequently adulterated. The nitric I 403 } and nitrous acid, and aqua fortis are composed of the same elements, oxygen and azote ; the latter, how- ever, in a state of dilution. Nitric acid may be prepared in the small way by putling nitrate of potash into a tubulated retort, con- necting the retort with a tubulated receiver,and pour- ing on it a little more than half its weight of sulphur- ic acid, and applying heat. The sulphuric acid will unite with the potash, forming sulphate of pot- ash, which will remain in the retort, and the nitric a- cid pass over, and be condensed in the receiver. By exposure to the light, the acid will be changed into the red fuming acid, improperly called nitrous acid. On the large scale, especially for the preparation of aqua fortis, iron vessels with stone ware heads, and a series of stone ware receivers are used. Common iqua fortis, or rather the aqua fortis duplicatus, is a mixture of equal parts of nitric acid and water. Nitric acid is capable of absorbing very different proportions of nitrous gas ; and when it is placed in contact with it, it first acquires a pale yellow col- our, then a bright yellow, and as the absorption goes on, it becomes dark orange, then olive, then a bright green, and when saturated a bluish green. The quantity of nitrous gas, thus absorbed, is very great. Dr. Priestley (1 p. 383,) remarks, that a quantity of acid equal in bulk to four penny weights of water, absorbed 130 ounce measures of gas, and then was not saturated. Sir H. Davy, (Researches p. 37,) has given a table of the component parts of the acid, of different colours and densities. The colour of ni- ( 404 ) trie acid depends also, in a degree, on the water k contains. If a fourth part, by weight, of water is ad- ded to yellow nitric acid, it will assume a green col- our ; and when equal parts of water are added, it be- comes blue. Nitric acid may be rendered colour- less, or deprived of its nitrous gas, by the agency of heat; hence yellow nitric acid becomes colourless in this manner. The gas carries with it, however, a portion of acid. As the saltpetre, which is used in the distillation of nitric acid, is generally impure, the acid obtained from it is more or less contaminated. Nitric acid in its most concentrated state should have the specific gravity of 1.1500. It should be perfect- ly colourless, and as limpid as water. The pres- ence of sulphuric and muriatic acid may be shown by diluting it, and adding nitrate of barytes and ni- trate of silver. If both the sulphuric and muriatic acids be present at once, it will be necessary to add nitrate of barytes as long as any precipitate falls, which will disengage the.sulphuric acid; and, after separating the precipitate, to add to the remaining fluid-nitrate of silver, which will throw down the mu- riatic acid in combination with the silver. NITROMURIATIC ACID. Nitromuriatic acid, or aqua regia is prepared by mixing due quantities of nitric and muriatic acid, or, as formerly, by dissolving muriate of ammonia in nitric acid. This acid is the solvent for gold and ( 405 ) platinum. If sulphuric acid be suspected, it may bt diluted with water, and examined with muriate of barytes. Nitromuriatic acid, if properly made should act powerfully on gold, and the solution when boiled furnishes nothing more than muriate of gold. MURIATIC ACID. Muriatic acid, or spirit of sea salt, is obtained by distilling muriate of soda with sulphuric acid. It is nothing more than water saturated with muriatic acid gas. The preparation of muriatic acid consists, there- fore, in the saturation of water with muriatic acid gas. This may be effected by causing the gas, as it proceeds from a retort containg muriate of soda and sulphuric acid, to pass through water in a series of Woulfe's bottles, or in Knight's apparatus; or by distilling a mixture of muriate of soda, sulphuric acid, and water, having at the same time a large re- ceiver, and connected, with one or two of Woulfe's bottles by means of a tube leading from the tubulure of the receiver. Muriatic acid is usually made on the large scale by distilling the mixture in the same apparatus as is used for nitric acid, with, however, some variations. \? muriatic acid is a compound of chlorine and hydrogen, therefore called hydrochloric acid by The- nard, the bleaching gas, (chlorine,) is prepared from it by sundry processes, which have for their object the separation of the hydrogen. Thus, if muriatic (. 406 ) acid be digested on the Uack oxyde of manganese, or on the red oxyde ol lead, its hydrogen will unite with the oxygen furnished by these oxydes and form water, while the chlorine gas will be evolved. If a mixture of muriate of soda, and oxyde of manga- nese be acted upon by diluted sulphuric acid, the same gas will be obtained. According to a more modern rationale of the pro- duction ofthe chlorine from these substances, con- sidering common salt free from water, the chloride of sodium, in which chlorine alone is combined with the metallic basis of soda (sodium,) water is said to be decomposed previously to the liberation of chlo- rine, and that its oxygen unites with its sodium, to form soda, and its hydrogen with the chlorine con- stituting hydrochloric acid. Now, in a mixture of chloride of sodium, oxyde of manganese, sulphuric acid, and water, the first effect is the decomposition ofthe water, the second the formation of soda, and the disengagement of hydrochloric acid, and the third and last, the action ofthe oxygen of the oxyde of manganese on the muriatic acid, which unites with its hydrogen, derived originally from the water, and chlorine gas is evolved, and water reproduced. Chlorine, we may observe, is used for bleaching, • either in the state of gas, or combined with water, or with lime as in Tennant's bleaching powder, or with alkali. It is the disenfecting gas of Morveau ; and its preparation and use, for destroying conta- gious matter, deleterious miasmata, may be seen in the article on aerial poisons. C 407 > Muriatic acid generally contains iron, which com- municates to it a yellow colour ; the pure acid being colourless. It may be detected in the same man- ner as recommended under the head of sulphuric acid. Sulphuric acid is also detected by the rea- gents we have mentioned. The specific gravity of muriatic acid should be 1.170. That of commerce is generally from 1.156 to 1.160. When muriatic acid is mixed with nitric acid, the product is the nitro muriatic acid. It is decomposed in the mixture ; and the new acid consists of nitrous acid, chlorine, and water. OPIUM When incisions are made, in the unripe seed ves- sels of the papaver somniferum, a milky juice exudes, which gradually concretes into a dark brown colour- ed mass. This is opium. The minutae ofthe process is unnecessary to men- tion, since opium is known to be the inspissated juice of the poppy, and the manipulations consist in forming it into cakes, rolls, or balls, and covering them with poppy, or tobacco leaves for transporta- tion. We may remark, that the cultivation of opium is extensively pursued in the East Indies; nearly 600,- 000 pounds weight of it are annually exported from die Ganges. The colour of opium is reddish brown, inclining ( 408 ; to black. It has a strong and very peculiar smell.— Several qualities are to be found in the shops; but the best is that usually called Turkey opium. It is generally more free of foreign matter ; and, for that reason, better adapted for officinal preparations.— Those acquainted with the appearance of opium, can always judge of its quality. It is, however, largely adulterated, and the detection of foreign substances is rather difficult. Opium, we observed, should be nothing more than the inspissated juice ofthe pop- py ; but it is adulterated by an extract of the plant, obtained by boiling; by a powder of the dried leaves and stalks, mixed with some kind of gum; by rice flour, and by other substances not quite so agreeable as these. In the East Indies when the opium is collected, it is beat up with honey and water; the former is add- ed to prevent its drying, and its quantity is sometimes so great as to soften its bitterness. Belon observes, that frequently a pound of opium contains only four ounces of pure genuine opium. The purification of opium, according to the pharmacopaeia, consists in dissolving it in twelve times its weight of proof spir- it, filtering the tincture, and evaporating it to dry- ness. Besides resinous and extractive matter contained in opium, which are distinct from the narcotic prin- ple, as it was called, there can be no question, that the peculiar properties of opium are owing to the presence of a substance possessing all the characters of alkali, which appears to exist in combination with • ( 409 ) t peculiar acid, and that when separated from the latter cannot be used even in small quanties without great caution. We have had occasion to mention the narcotic and other properties of opium, in our article on poisonous vegetables, he. which see. In Europe it was first introduced as a medicine by Paracelsus; but in the east it has been used from time immemorial as an intoxicating drug.* What is called the narcotic principle was obtained from opium, by Desorme in 1803, and was found to contain the poisonous and intoxicating qualities of opium ; but this principle is found to be a new ve- getable alkali, called morphia. The preparation of morphia may be effected by boiling a concentrated infusion of opium with a small quantity of magnesia; a deposite will be obtained, which is to be collected on a filter, washed with cold water, and acted upon by weak alcohol in a moder- ate heat for some time. Very little morphia, but a large proportion of colouring matter, is separated. The acid matter, after being drained in a filter and washed with a little cold alcohol, is to be boiled with a large quantity of rectified alcohol; the solution filtered, and suffered to cool, when crystals of mor- phia will be formed. As opium contains meconiate of morphia, the the- * Several memoirs have been written on the manufacture of opium. In the British Journal of Scienct (8th and 9th vols.) and in the lstvol. ofthe Edinburg Phil. Jour, are two import- ant papers on the manufacture of British opium. It has been made in die United States 3n ( 410 ) ory of the process, it is obvious, is the decomposi- tion ofthe meconiate by the magnesia, and the mor- phia is displaced. Without enumerating all the chemical characters of this substance, morphia unites with the acids forming salts, and acts with great energy on the animal economy, so much so in- deed, as Dr. Ure informs us, that a grain and a half taken at three different times, produced such violent symptoms upon three young men, that Serturner was alarmed lest the consequeaees should have proved fatal. With regard to the other constituent of opium, the meconic acid, it will be sufficient to add, that it may be prepared by first precipitating the morphia .from a solution of opium by ammonia, and adding to the remaining fluid muriate of barytes, by which the meconic acid with other substances is thrown down. Alcohol is added to remove the extract, and sulphur- ic acid to separate the barytes. The meconic acid is now left in combination with a portion of the mor- phia; from which it is separated by repeated solu- tions and evaporations. This acid unites with basis, and forms a distinct class of salts. Mr. Vogel asserts, although it is denied by Robi- quet, that meconic acid will precipitate iron from its muriate, and as its power of precipitating solutions ol that metal is so great, he proposes it as a more deli- cate test than even the ferrocyanate of potash. Vinegar, we remarked heretofore, has been usual- ly prescribed to counteract the effects of a dangerous dose of opium; but in the opinion of Orfila, it aggra- ( 411 ) vates it. The proper remedy, no doubt, consists in the immediate administration of powerful emetics, as sulphate of zinc or sulphate of copper. ALCOHOL AND iETHER. Spirit of wine, alcohol, and ccthers, are frequently sophisticated, or not of the proper strength. The best and most decisive mode of ascertaining the strength of spirit of wine and of aethers, is by deter- mining their specific gravity. Rectified alcohol should be 800 to 1000, common rectified spirit of wine 835 ; proof spirit 820; sul- phuric aether, if purified, 729, commonly 750; sweet spirit of nitre 834, he. The aether should be entire- ly free from acid, and, therefore, ought not to red- den the colour of litmus. Sulphuric aether should not affect muriate of barytes. With respect to the various mixtures of alcohol and water, with and without addition, as we find them in brandy, rum, gin, whiskey, he. the subject has already been noticed, and the means of detect- ing the different frauds as practised by distillers, and dealers in those liquors, in a preceding lecture. ESSENTIAL OILS. The essential or volatile oils differ in regard to their volatility and peculiar aroma or flavour, from the fixed oils; the former are obtained by distillation, and the latter by expression. ( 412 ) Volatile or essential oils, it is to be observed, dil- fer in their consistence. Lavender, rosemary, and rue, furnish, for example, very fluid oil; the oils of cinnamon and sassafras are thicker. Some constant- ly preserve their fluidity; others become concrete by the slightest impression of cold ; and others again, possess the concrete form, as the oils of roses and eli- campane. Volatile oils differ from each other in an- other respect, besides their peculiar odour, by which they are known and designated ; namely, they vary in their colour and weight: the oil of roses is white; oil of lavender, a light yellow; that of cinnamon of a brown yellow : oil of chamomile of a fine blue; oil of millefoil, of a sea green, &c. and, generally, are so light as to swim on water, although some are heavier than water, as the oils of sassafras and cloves. It is remarked, that the taste of the volatile oils in general is hot, but do not always partake of the pun- gency ofthe plant, a fact that the pungency does not uniformly exist in the essential oil, but in a bitter. principle totally distinct. We have an example of this in the oil of pepper, which has no pungency, and in the oil of wormwood, which is not bitter. The quantity of essential oils, furnished by plants^ is variable, nor is the proportion always the same, owing to various circumstances : as, for instance, some afford most when green, others when dry, be- sides the influence of accidental circumstances, as the soil, climate, time of extraction, and the age of the plant. A fraud has been practised in the preparation of ( 413 ) 3ome essential oils, which may be proper to notice; the leaves or flowers are soaked in olive oil previously to distillation, and some ofthe oil, it is said, rises with the volatile oil. In this way, we are assured, nearly all the oil of chamomile sold in the shops is pre- pared. It is to be observed, that, in the distillation of a flower, for the purpose of procuring its oil, wa- ter is always put into the still; and the oil that rises, in the present instance, must be that portion of the fixed oil which was absorbed, and no doubt assimi- lated with the essential oil, as the quantity of the lat- ter is considerably increased. But olive oil, or the oil of ben, which has no taste and flavour, has been used to extract essential oil by mere digestion. There are several methods used to retain the ar- omatic principle. The art of the perfumer consists in applying the aroma, or odorous principle, at pleasure to various substances. Perfumes are ei- ther dry or liquid. The perfumed bags, or sachets, contain mixtures of aromatic plantF, or aromas in their native state; perfumed powders receive their fragrance from aromatic oil; and sundry pastes are perfumed in the same manner. Liquid perfumes are nothing more than sundry odoriferous waters, prepared either by distillation from flowers, or from the essential oil, or solution of the oil in alcohol.— Scented spiritous cordials are various liquors con- taining so ne aromatic oil, and sweetened with sugar. Cordials, we may remark, are nothing more than spiritous liquors distilled from certain substances, which communicate die peculiar taste and smelk 35* ( 414 ) and mixed in due proportions with sugar, or sirup. The eau divine of the French, for example, is a scent- ed cordial made by distilling citron with orange- 0ower water and spirit of wine, and adding to the distilled liquor a sufficient quantity of sugar. The remark of Mr.. Chaptal on the subject of per- fumes is correct; viz. "that in all perfumes which are a little complicated, the nose is the best chemist that can be consulted; and a good nose is as requis^ he and essential to a perfumer, as a strong head is to a geometer." Essential oils on account of their value are often. found adulterated, either with cheaper volatile oils, with fixed oils, or with alcohol. Distillation will dis- cover the fixed oils, as heat elevates the essential oils, and leaves the fixed oils; and if paper be mois- tened with the oil, and held he fore the fire, the fix- ed oil will leave a stain. If the oil be entirely essen- tial, no stain will remain, on the paper. If alcohol be added to an adulterated essential oil, which con- tains a fixed oil,.it.will leave the fixed oil on evapor- ation. The presence of cheaper essential oils is determined by, the smell. To essential oils, alcohol is often added to increase their quantity. This solution of essential oil in al- cohol is transparent, but looks thin. The detection is easily made by adding water, which, if there be- any alcohol, a milkiness will ensue. The difference in essential and fixed oils, with respect to their chemical characters, is well defined. Fixed oil»r we remarked, are generally obtained by ( 415 ) pressure, and essential oils by distillation; and moreover cannot be voltilized without decomposi- tion, which takes place at a temperature of about 600 degrees. Essential oils, on the contrary, evap- orates at a moderate temperature. Fixed oils, gen- erally speaking, are insoluble in alcohol, whereas es- sential oils are readily taken up by that fluid, and such solutions become turbid on the addition of wa- ter, owing to the union of the alcohol with the wa- ter, and the consequent separation of essential oil.— Fixed oils when exposed to the air become viscid, and acquire a degree of rancidity, but essential oils placed under the same circumstances totally evap- orate. Linseed and nut oil, when boiled with li- tharge, acquire the property of drying when expos- ed to the air, and hence become drying oils. In perfumed essences, the sssential oil is combined with alcohol; in distilled waters, the water is impreg- nated by the oil. Very often a scentless vegetable oil is impregnated with the aroma of another oil. The oil, or atter of roses, is frequently mixed witholive oil. This fraud is discoverable by evaporating a portion of it when the olive oil will be left. The Italians prepare from the flowers of the jasmine (jassaminum-officinale,) a grateful perfume, by soaking cotton in the best sal- lad oil, and placing in glass vessels alternately lay- ers of this cotton, and of the flowers. After remain- ing for some time to soak, the latter are found to have given the whole of their fragrance to the oil ir the cotton. The oil is then pressed out for use, ( 416 ) The essence of bergamot is obtained from the rind ofa variety of orange much cultivated near the town of Bergamo, in Italy, whence it has obtained its name. The rind is cut into small pieces, and the oil is pressed out into glass vessels. The true Russian oil, which is used for the pur- pose of making the hair grow, is nothing more than depurated bear's grease, and is therefore an animal nil. It is frequently adulterated with sweet oil. In the preparation of certain perfumes, the oil of ben-nut is highly recommended, as it does not grow rancid by long keeping like the common expressed oils. It is impregnated with the odour of jasmine, and other flowers, by stratifying them with cotton dipped in oil as above mentioned. OLIVE OIL. We mentioned that olive oil was liable to be con- taminated with lead, either from the manner it was prepared, or by standing in leaden cisterns, and that the detection of lead was effected by shaking a por- tion of suspected oil in aqueous sulphuretted hydro- gen, which, if it were present, occasions a black or dark brown colour. Olive oil is sometimes adulter- ated with the fixed oil of certain seeds; to detect which nitrate of mercury has been recommended.— The nitrate, for this purpose, is prepared by dissolv- ing six parts of mercury, without heat, in seven and a half parts of nitric acid, of the specific gravity of 1.36. This solution when shaken with olive oil, so- i 417 ) i.difies in a few hours; a criterion ofthe absence of other fixed oils; but if adulterated, it does not be- come solid. This test we give on the authority of professor Brande, ofthe Royal Institution. The fruit ofthe olive tree (olea europia,) which furnishes the salad or olive oil by pressure, when in- tended to be eaten, must be steeped in an alkaline lixivium, and then pickled in salt and water, to re- move an acrid, bitter, and unpleasant taste. In the- preparation ofthe oil it is observed, that if the olives be indiscriminately gathered and heaped together, sound an unsound, without selection, the oil is always bad. OIL OF CAJEPUT.. This oil is seldom, if ever, found free of adultera- tion.. The real oil is obtained.by the distillation of the melaluca leucandron of Linnasus. The oil is highly fragrant and aromatic, and a few drops of it will destroy insects. It is of a green colour, with a smell of turpentine, and the taste of peppermint. It is the best solvent for the caoutchouc,or Indian rubber. The genuine oil is rarely met with, and its place is generally supplied with a preparation of turpentine and camphor, with the oil of cardamom, and colour- ed with some green vegetable. Thurnberg describes t it of a grass green colour, equally fluid with ardent spirits, burning or evaporating without leaving aresi- due. The smell resembles that of camphor, mixed with turpentine. Goetz says, that it has a terebin- ( 418 ) thinate odour, followed by that of savine. He con- siders it genuine when a drop rubbed on the tem- ples occasions a pungent pain in the eye, with a dis- charge of tears. Many travellers seem to agree that its green colour is not essential to it, but in some measure adventitious, owing to an ad- dition of the berries and leaves. Some again think that it is owing to copper; the presence of which, however, may be detected by adding liquid ammonia. The Dutch formerly made it by adding to the oil of rosemary some camphor, with a little oil of cardamom, and giving the mixture a green co- our. An imitative cajeput oil is made usually by drug- gists, in the manner before spoken of, namely, by dissolving camphor in oil of turpentine, adding eith- er oil of cardamom or oil of rosemary, and colour- ing it by digesting it-on -^ome green vegetable, or green grass. The genuine oil should evaporate entirely, and at a moderate temperature, without leaving any re- siduum : but if the fabricated oil be subjected to the same experiment, the turpentine will evaporate, as well as the essential oil of rosemary or of carda- mom, and if the heat be not carried too high,the cam- phor and the colouring matter will remain. If alcohol be digested on this residue, the camphor will be dissolved, which may be separated by the addition of water. Alcohol may be mixed with a pcrtion of each of the oils, the genuine and spurious,. and afterwards examined, ( 419 ) CAMPHOR. Camphor, in its crude state, as it comes from the East Indies, principally Japan, where it is obtained from the laurus camphora, by sublimation, is always contaminated with impurities, from which it is freed by a second sublimation in glass vessels, by using a given quantity of lime. It is then in a semitranspa- rent and concrete state. In many respects pure camphor rssembles the essential oils ; by its volatil- ity, inflammability, and solubility in alcohol. It is converted into an acid, the camphoric, by distilla- tion with nitric acid. There are several species of camphor, such as the common, the camphor of vol- atile oils, and that obtained by heating oil of turpen- tine with muriatic acid. The best crude camphor should be in large grains, very white, without the appearance of dirt; but as it is seldom imported perfectly pure, being adulterated with foreign matter, usually earth, the detection of earthy matter, and its quantity determi- ned, may be effected by exposing a given weight on an iron plate to a heat sufficient to evaporate the cam- phor. The residue, if any, will show the amount of foreign admixture. This may be examined by solu- tion in acids, and the usual reagents. The same fact may be learned by dissolving agiv- en weight ofthe camphor in alcohol; and ascertain- ing the quantity of insoluble residue. The camphor may be separated from the alcohol by the addition of water, and collected on a filter, and dried, and ( 420 ) weighed. There is, however, a large quantity ot water in crude camphor. I have not seen any that did not contain from five to ten, or more per cent of that fluid. Exposure to a very moderate tempera- ture, will evaporate the water. The camphor has then a dry feel. The refining of camphor, from the crude, as it is brought to our market, is a process ex- ceedingly simple, notwithstanding so much has been said on the subject. A glass sublimer, or balloon as it is called, usually holds from four to six pounds.— The camphor is made fine, and introduced into' it, along with one or two ounces of dry hydrate of lime (lime slacked and dried,) or pulverised quicklime. The balloon is now placed in a sand bath, and heat applied. The camphor melts, and evaporates, and condenses on the upper part of the glass, and takes the shape of it. This head is usually from an inch to two inches in thickness. The glass is broken in order to get it out, and the residue is sometimes re- sublimed. Refined camphor is never contaminated. Tt should, however, dissolve wholly in alcohol. SPERMACETI AND TALLOW. It may be necessary sometimes to distinguish be- tween spermaceti and tallow, or more properly, whether the former has been adulterated with the latter, or other fatty substances, as in spermaceti candles. Candles which are sold as the pure sper- maceti are seldom, if ever, free from the adnvxture of fat or tallow; and the fraud cannot well be detec- ( 421 j ted unless we attend to the chemical property of each substance respectively. Spermaceti is a peculiar oily substance obtained from the cranium of the spermaceti whale, the phys- eter macrocephalns, and from some other species. It is first mixed with some liquid oil, which is separa- ted by means ofa woollen bag, and the last portions are removed by an alkaline ley, and the spermaceti is afterwards purified by fusion. It is a white sub- stance, having more or less a crystalline structure, and scarcely any taste. It is distinguished from most other fatty bodies hy the crystalline appear- ance, which it always assumes. When sufficiently heated, it may be distilled over without much al- terations. It is soluble in boiling alcohol, but sepa- rates again as the solution cools. One hundred parts of alcohol, ofthe specific gravity .816 dissolve 6.9 parts of it. It is also soluble in aether, and in hot oil of turpentine, but precipitates as the solution cools. It forms an emulsion with hot ammonia, which is neither decomposed by cooling, nor by water ; but the spermaceti is immediately precipitated by the ad- dition of an acid. Tallow, suet, and lard will not distil, like sperma- ceti ; but they afford by destructive distillation, first a portion of water, and then a white oil, very small indeed, which finally concretes, and a black mass remains in the retort. If spermaceti is pure, it will distil entirely; if it contain suet or fat, it will leave a black residuum, and at the same time an abuudance of carbonic acid and 36 ( 422 ) carburetted hydrogen come over. In this case also the odour is so offensive and powerful, that it is ab- solutely impossible to endure it. Fat is insoluble in alcohol and aether; spermaceti is solubje in these fluids. Therefore, a mixture of spermaceti and tal- low when digested in alcohol will be decomposed; the spermaceti taken up, and the tallow or fat re- main. By this means the quantity of tallow may be ascertained. The acids have scarcely any action on spermaceti, if pure; but if a little nitric acid is poured on fat, it converts into a yellow coloured substance, which Fourcroy considers an oxyde of fat. If spermaceti, therefore, be adulterated with fat, when treated with nitric acid it will become yellow. The most conclu- sive character seems to be the solubility of sperma- ceti, and the insolubility of fat, in alcohol. This fact added to the property of being distilled, and without leaving a residue, will serve to distinguish one frdm the other, and to show the presence of fat or tallow in spermaceti. Alcohol, we must observe, when boiled on hog's lard, takes up two proximate princi- ples called stearin and elain. WAX AND TALLOW. In the preparation of wax candles, tallow may be added. The fraud may be discovered by using al- cohol. If boiling alcohol be poured on wax, it will dissolve it. Rather more than 20 parts of alcohol are required to dissolve one of wax. As the solu- ( 423 ) tion cools, the greater part of it will precipitate. If the wax contain tallow or fat, the latter will remain undissolved, and may be examined. The residue may contain a principle of wax, called myricin, and, therefore, the solution in alcohol cannot be altogether relied on. Dr. John ascertained, that when wax is digested in a sufficient quantity of boiling alcohol, it is divided into two distinct substances; one, called £erin, is taken up by the alcohol, and the other, which he named myricin, remained undissolved.— By examining, however, the residue, we may judge of its nature. When wax is boiled with a solution of fixed alka- lies in water, the liquid will become turbid, and after sometime the soap will separate, and swim on the surface ; and if an acid be added, the wax will separate in flakes, without much alteration in its pro- perties. Fat treated in that manner, will form a soap, and the addition of acid will unite with the al- kali, and separate the fat, but not in flakes. The soap too, is uniform in its appearance. But there is one character by which the purity of wax may be judged. If pure, sulphuric, muriatic, and nitric acid will have no action upon it, whereas if it contain the least quantity of tallow or fat, nitric acid will colour it more or less yellow, and the acids have more or less action. Wax when exposed to a temperature of 150 deg. melts, and at a higher temperature is converted into vapour, which burns with a brilliant flame. At a red heat it burns in contact with air ( 424 ) The fruit ofthe tallow tree (croton sebifera,) fur- nishes the Chinese with a kind of tallow for the man- ufacture of candles, which is not equal to wax or spermaceti, but are more firm than those of tallow. The candles made from this substance are very white, but are sometmes coloured by adding a little vermillion. WHITE AND YELLOW WAX. The former is the bleached yellow wax, called al- so virgin wax; the latter is the ordinary wax of com- merce.* Wax, we observed, should be soluble in boiling alcohol; but there will be more or less ofthe myra- cin separated, which must be taken into considera- tion. The purity of white wax may be determined pretty accurately by its physical characters; but it may, nevertheless, be submitted to experiment.— Yellow wax is seldom adulterated. It may be puri- fied by melting it, and suffering it to remain undis- turbed for a short time before it is poured off. *What is called the myrtle wax, which is made in this coun- try, is extracted from the seeds or berries of the myrica cerife- ra, and also from thepela of the Chinese. The berries are merely put into a kettle with water and boiled, and then gent- ry squeezed ; the wax is melted out, and swims on the surface. It is skimmed off, strained and suffered to become cold. It burns with a white flame, with an agreeable aromatic odour and produces little smoke. The coating of leaves is of a waxy nature ; also the covering of resins, plums, oranges and similar fruits. ( 425 ) HAIR POWDER. Hair powder is an article frequently adulterated. It should consist of nothing more than pure feculae, obtained either from grain, or potatoes. The man- ner of preparing this feculae is easy. The grain is ground, as is usually the practice, or the potatoes dri- ed and rasped, or powdered, and then washed in an abundance of cold water, by which the feculae is se- parated from the other proximate constituents. Hair powder should be impalpable, very light, and when mixed with cold water, neither form a paste, as with flour, nor show any gritty or hard sediment. Flour with which it is more frequently adulterated, contains a considerable quantity of gluten ; and as starch or feculse will not make a paste unless heat be applied, (and then a tremulous jelly like sub* stance, more or less transparent,) the detection of gluten is readily effected. Hair powder, if pure, and washed in cold water with the hand, will leave no gluten ; but if, on the contrary, it contains it, and consequently flour, more or less gluten will be sep- arated, while the feculae or starch will precipitate.— The cold water, in which hair powder is diffused, should not be contaminated with saline, or other sub- stances. Chalk, or whiting, is another substance used in the sophistication of hair powder. It may be detected by adding a very dilute muriatic acid ; an efferves- cence will ensue ; and the fluid, when filtered, and tested with oxalate of ammonia, will show the pres- 36* ( 426 ) ence of lime. The same may be effected, thougfi less perfectly, by boiling the whole in water, and straining out the feculae; then treating the insoluble part with muriatic acid, and examining the solution as before. If any of the white clays be mixed with hair powder, which, like chalk and gypsum; must add greatly to its weight; the discovery may be effected by testing the solution for alumina,.and the insoluble part will point out the presence of silica. Calcined sulphate of lime or gypsum, may be detected by boiling the hair powder in a large quantity of pure water; then strain, and filter the fluid. If we add to separate portions of this fluid the usual tests for sulphuric acid and lime, the presence of gypsum will be rendered manifest. But these substances are heavier than hair powder, and are simply mechanic- al mixtures, if the adulterated hair powder be mixed with water, they will fall to the bottom. By burn- ing off the vegetable matter of hair powder, (which, if pure, should be consumed entirely, gluten not be- ing here considered,) the foreign impurities may be detected, and their quantity estimated. This resi- idue may be examined by the rules before men= tioned. There is another process, which may be used to discover whether hair powder is adulterated with lime, by using sal ammoniac. A small portion ol this salt when put to the suspected hair powder, and a little warm water poured on; if the powder has been adulterated with lime, a strong smell of vola- ( 427 ) tde alkali will arise from the mixture. This ne*a live proof, as we infer the presence of lime by t°he smell of ammoniacal gas, (the lime decomposing tht muriate of ammonia,) is sufficient to warrant that conclusion. Hair powder is sometimes scented, and sold as perfumed hair powder. The perfume consists of the essence of bergamot, oil of roses, and frequently powdered orris root, and sometimes of a mixture of sundry aromatic oils. "*• ANATTO. The seeds of the bixa orellana are separated from the capsules, and pounded and steeped in water for weeks or months, and. then subjected to the press, by which the colouring matter is obtained. This col- ouring matter is anatto. It appears to be confined to the surface ofthe seed. Anatto is usually in hard cakes or rolls, brown without, and red within. It should be perfectly soluble in alcohol, and in weak alkaline solutions. A decoction of anatto in water has a peculiar smell, and disagreeable taste. Its co- lour is reddish yellow, and alkalies render it orange yellow. The acids should throw down from this mixture an orange coloured precipitate. The che- mical nature of this colouring matter appears to be intermediate, between extractive and resin. Anatto is used in dyeing, and, as a colouring in- gredient for cheese, and is sometimes used to give a rich colour to. butter. It has also been mixed with chocolate. ( 428 ) Those who roll it from the rocou generally adul- terate it, sometimes with Spanish brown, and render it soft by using molasses. In England it is frequent- ly adulterated with vegetable matter, and the colour is heightened by the addition ofvermillion. Some- times the vermillion itself is adulterated with red lead; and hence anatto, thus adulterated, has com- municated deleterious properties to cheese. Anatto is soluble in alcohol. If any residue should be left, it may be examined for Spanish brown, vermillion, or red lead. When a portion of the anatto is dried, and mixed with chlorate of pot- ash, and subjected to heat in a crucible, the vegeta- ble matterwillbe burned,and if any mineral adultera- tion be present, it will show itself in the remaining residue. For red lead, the residue maybe acted on by acetic acid, and the solution tested by aqueous sulphuretted hydrogen. If ochre be present, the. so- lution will contain iron, which may be examined by tincture of galls, and the residue will be more or less gritty, indicative of silica. To detect vermillion the best mode is to dissolve the anatto in alcohol, •and mix the sediment with lime, and distil it; the mercury will pass off, and be condensed in glob- ules. TURMERIC. Turmeric or curcuma longa, called the Indian long rooted turmeric, is brought from the East Indies.— The root is ground to powder for use. It has a ( 429 ) slight aromatic and bitterish taste, and somewhat disagreeable smell. It gives out its virtues both to water and to spirits; by distillation with water, a small quantity of essential oil is obtained and from the remaining decoction a bitter extract is procured by evaporation. The spiritous extract retains near- ly the whole virtues of the root. The infusion, as well as the tincture, is rendered brown by alkalies; hence it is used as a test for uncombined alkalies. The alkaline earths, as magnesia, affect it in like manner. To water it gives a yellow, but to alco- hol a red colour. If the alcoholic tincture be appli- ed to hot marble, it will impart a durable colour. Turmeric is chiefly used for a colouring ingredient. It forms a component part of curry powder* Tur- meric powder is often adulterated either with flour or Indian meal, or more commonly with yellow pease, a fraud practised considerably in London. The de- tection of farinaceous substances may be accom- plished in the manner already spoken of: viz. by separating the fecula and gluten, if the latter be pre- sent, by means of cold water. If the suspected tur- meric be boiled in water, the decoction will become thick and pasty, thus indicating the presence of flour or pease. If starch be dissolved in the water, iodine will discover it, by forming an iodine of starch; a compound ofa blue colour. PERUVIAN BARK. Although there are various descriptions of thi* I 430 ) bark, commonly called yellow and red, which pos- sess different medicinal powers, and which are men- tioned by writers on the materia medica, yet both the pulverised yellow and red bark have been con- siderably adulterated ; the former with the quercit- ron, and the latter with the bark of the cherry, to which bol armen is added. It is necessary to notice the chemical characters of Peruvian bark. The presence of the bark of the quercus nigra may be known by its astringent taste, and boiling it in wat- er, which will produce a yellowish brown colour.— This decoction is rendered lighter by acids, and darker by alkalies. Muriate of tin gives a copious bright yellow precipitate ; sulphate of iron a dark ol- ive precipitate; and sulphate of copper a precipitate of a yellow colour, inclining to olive. The colour of the genuine red Peruvian bark is reddish brown, and has a slight bitter taste, with more or less astringency. Water in which the pow- dered bark is macerated, acquires the property of reddening vegetable blues, and contains a portion of citric acid, some muriate of ammonia," and muriate of lime. There is also besides extractive matter, a portion of resin, tannin, kinic acid, lime, and bit- ter principle. The admixture of bol armen, or any other earthy substance is readily detected by burn- ing off the vegetable matter, or by diffusing it in wa- ter, when the earth will be deposited, asd the bark suspended. We recollect that a quantity of red spurious bark was offered for sale in Philadelphia, in the quill. (' -ui ) and on inspection was found to be the common yel- low bark dyed with a decoction of log and red wood. On another occasion a fraud of a highly criminal na- ture was practised in the adulteration of bark, by the use of litharge as a colouring ingredient, which pro- duced very serious consequences. Litharge may be detected either by putting the bark in water, when it will precipitate, and the precipitate maybe exam- ined by.solution in acetic acid, and the addition of sulphuretted hepatic water; or by burning it with chlor- ate of potash,and examining the residue,or submitting it to the action of heat -on charcoal, when metallic lead will be obtained. Bark if dyed in the quill, with redwood and logwood, when boiled in water, and the decoction examined by sulphate of iron, mu- riate of tin, sulphuric acid, he. will readily be di«- eovered- COCHINEAL. This insect furnishes the colouring matter foi scarlet dye, which is also the basis of lake and car- mine.- Lake is a combination of carminium and al- umina, and carmine is a mixed precipitate consisting of animal matter, carminium, and oxyde of tin, or alumina. Cochineal may indeed have its colouring matter extracted, and then dried, and made to ap- pear like, and sold as, the cochineal of commerce; but this fraud is readily detected by making an infu- sion of the insect in hot water, which, of course, will not impart any colour, or very feebly. \ com- ( 432 ) parative experiment may then be made, by using some of the genuine cochineal; and, if necessary, the infusion or decoction tested with muriatic acid, alum, muriate of tin, he. SPANISH LIQUORICE. LIQUORICE BALL. Spanish liquorice, also called black sugar, is an extract obtained from the root of the glycyrhiza glabza. It is said that more than two hundred tons weight of it are annually manufactured in Spain, a considerable portion of which is sold to the London brewers for brewing. It contains a peculiar kind of sugar, starch, gluten, a brown thick resinous oil, and some earthy salts. Liquorice powder is frequently adulterated with flour. The detection is rather difficult, but never- theless may be attempted in the usual manner for discovering gluten, and feculae. ISINGLASS, OR FISH GLUE. A gelatinous substance obtained from the accipen- ser sturio, and several other kinds of fish, is called icthyocolla, or isinglass. The internal skin is boiled in water, and the decoction is strained, and inspissa- ted, and formed into convoluted pieces. The sounds and air bladders of fresh water fish, in general, fur- nish the most flexible and transparent isinglass. It has been made from the sturgeon, and other fish in rhe United States. Boiling the sounds and air blad- ( 433 ) ders, he. gives the purest isinglass; but the usual process consists in separating the exterior membrane, cutting the bladder, &cc. lengthwise, and forming them into rolls, or small pieces, and drying them. A very inferior kind of fish glue is prepared from sea wolves, porpoises, sharks, cuttle fish, whales, and all fish without scales. The tails, fins, &c. are boil- ed in the same manner as in forming ordinary glue. There are various qualities of this substance sold in the shops. Good isinglass may be recognised by its white co- lour; by its degree of transparency; and by its free- dom from smell. It should dissolve almost entirely in water, and when mixed with a solution of tannin be entirely precipitated. One hundred grains of isinglass were found by Mr. Hatchett to contain ra- ther more than ninety-eight of soluble matter. Isinglass is used in lieu of the white of eggs for clearing of coffee, in the clarification of spiritous li- quors, in the purification of blanc maunge, and in the manufacture of English court-plaster. A solution of isinglass, sufficiently concentrated, if often mixed with calves' feet jelly. Even the add- ition of wine and spices to isinglass jelly, in the same manner as to calves' feet jelly, will so nearly re- semble it, that they can scarcely be distinguished. If one part of isinglass be dissolved in one hun- dred and fifty parts of hot water, the solution on cooling is wholly converted into a jelly ; but one part of isinglass in one hundred and fifty parts of water, ^7 ( 434 ) does not become concrete, though it is more or less gelatinous. GLUE. Glue is extracted from the cuttings and pairings ol skins, horns, and the hoofs and ears of horses; oxen. calves, sheep, Sic. by first soaking them in lime wa- ter, and afterwards boiling them, by which the gelat- in is extracted. Glue differs in its strength, and hence some is pre- ferred to others. Good glue is distinguished from bad by holding it between the eye and the light. If it appears ofa strong dark brown colour,and lree from cloudy or black spots, it is considered good. The best glue is said to swell considerably without melt- ing, by three or four days immersion in cold water, and recovers its former dimensions and properties by drying. Glue which appears thick and black, is usually melted over again and some fresh added.— Glues .are found to differ in consistence, colour, taste, smell, and solubility. Some will dissolve by agita- tion in cold water, which is said to be a proof that it wants strength, while others are only soluble at the point of ebullition. Glue is perfectly soluble in wa- ter, forming a viscid fluid, which, when dry, pre- serves its tenacity and transparency in every part.— In proportion to the age and strength of the animal from which it is produced, it has more solidity, co- lour, and viscidity. To obtain glue as colourless as possible, a very small quantity of water is used for ( 435 ) extracting the jelly, and a moderate heat is used it evaporating it. Flander's glue owes its whiteness and transparency to this treatment. A colourless glue, called size, is procured from the skius of eels, vellum, parchment, different spe- cies of white leather, he. Gelatin forms a constitent part ofthe solid parts of animals, and, therefore, an essential part of bones, ligaments, tendens, membranes, skin, muscles, hair, he. Gelatin is characterised by certain properties, the most common and familiar is its precipitation from its solution by tannin, a combination which is formed in the process of tanning leather. See Portable Soup. ADULTERATION OF ARSENIC. We have already noticed the characteristic pro- perties of arsenic, or rather of arsenious acid. White arsenic, white oxyde of arsenic, and arsenious acid, names which imply the same substance, may, if pur- chased in powder, be frequently found adulterated. The adulteration may consist of carbonate of lime, sulphate of lime, carbonate of barytes, or sulphate of barytes. If muriatic acid be poured on it, it will cause an effervescence if carbonic acid is present.— The solution may be examined for lime by oxalate of ammonia, and for barytes by sulphuric acid. Sul- phate of lime may be discovered by boiling the ar- senic in a large quantity of water, saturating the ar- ( 436 ) senious acid thus taken up by potash, and adding to separate portions of the filtered liquor muriate of ba- rytes, and oxalate of ammonia. If arsenic, contain- ing sulphate of barytes, be mixed with an equal quantity of carbonate of potash, and boiled in water for some time, an arsenite and sulphate of potash will be formed, and remain in solution, and carbonate of barytes found at the bottom.* The latter may be collected on a filter, dried, and its weight ascertain- ed. When dissolved in nitric acid, and the nitrate exposed to strong heat, pure barytes will be left; or, if the solution be acted upon by sulphuric acid, sul- phate of barytes will precipitate, which, when weigh- ed, will give the original quantity of the sulphate contained in the arsenic. The solution of arsenite and sulphate of potash, may be examined for sul- puric acid by the usual reagents, As neither the carbonates of lime and barytes, nor the sulphates of the same earths, are volatilized hy heat, pure arsenious acid being volatile; we may detect in a general way the presence of these sub- stances by exposing the arsenic to the action of heat. The residue will afford a pretty correct criterion of the quantity of foreign substances, making due al- * The decomposition of sulphate of barytes by carbonate of potash, is usually effected by reducing the crystallized sulphate of barytes to powder, mixing it with three parts of carbonate of potash, and fusing the mixture for half an hour in a silver crucible. The fused mass is then boiled in water. The carbonate of barytes, thus produced, when digested in nitric acid, and the nitrate exposed to a strong heat, will produce pure Harytes. i 43? ) iowance for the escape of carbonic acid. It may be examined by solution in acid, &c. as before men- tioned. Before the blow pipe, white arsenic should en- tirely volatilize in a white smoke with a strong odour of arsenic. It is blackened by the action of com- bustibles. It is distinguished from arseniate of lime by its solubility in water, which is about as one to eighty times its weight of water, at 60 degrees.— White arsenic, if required pure, should be purchased in the lum;. RED AND YELLOW SULPHURET OF AR~ SENIC. These sulphurets are seldom adulterated. Their purity may be determined by exposing them to heat. The red sulphuret, or realgar, melts easily, burns with a bluish flame, and is volatilized by the blow pipe, exhaling white fumes of arsenic, and the odour of arsenic and sulphur. Nitric acid poured upon it, causes its colour to disappear. Realgar is a lively red, often more or less tinged with yellow. Its streak and powder are orange yellow. The yellow sulphuret or orpiment is usually of a lemon yellow colour, which is often shining and very beautiful. Its streak and powder have the same co- lour as the mass. When exposed to heat, it exhibits the same char- acters as the red. Hence, before the blow pipe, it is principally volatilized with a white smoke, accom- 37* ( 438 ) panied with the odour of arsenic and sulphur. A small earthy residue usually remains. It melts some- what less easily than realgar, and, on cooling, as- sumes an orange tinge. The experiments of Proust and Thenard show, that the arsenic in both the sulphurets is in a metallic state, though combined with the sulphur in different proportions. Realgar, if melted with sulphur, pro- duces orpiment; and orpiment when combined with an additional quantity of arsenic, is converted into realgar. The Turks use orpiment in the depilatories, which serves to render bald the top of the head. The Chi- nese use realgar in medicine. ARSENITE OF POTASH. The pharmaceutical preparation sold in the shops, under the name of Fowler's solution of arsenic, is usually prepared from the powdered white arsenic, which, we have seen, is often adulterated. When white arsenic, thus impure, is boiled with a solution of potash, we not only lose a great part of the strength of the preparation, but that which is made is contaminated. The presence of sulphate of ba- rytes, for instance, would produce in the fluid sul- phate of potash; which may be determined by the addition of muriate of barytes, or by evaporation and crystallization. In preparing Fowler's solution, the white arsenic ( 439 ) should be powdered from the lump, which we have generally found to be pure. If arsenite of potash be mixed with the ammonia- ted sulphate of copper, or rather for this experiment with acetate of copper, an arsenite of copper, or Seheele's green will be precipitated, and acetate of potash remain in solution. If, after separating the arsenite of copper by the filter, we examine the fluid with muriate of barytes, and the arsenical solution was free from sulphate of potash, no precipitation will take place. WHITE OXYDE OF BISMUTH*. This preparation is used in medicine in dyspeptic diseases. It is formed in the same manner as the majistery of bismuth. It is called subnitrate of bis- muth. * Salts of bismuth are soluble, but they generally decompose on the addition of water. The solutions of bismuth in acids ir usually colourless; and water, when added, occasions a white precipitate, composed of the oxyde of bismuth, and a small por- tion of acid. Ferrocyanate of potash produces with these solu- tions a white precipitate, hydrosulphuret of potash a dark brown, and gallic acid a light yellow precipitate. A plate of (in or copper, precipitates the bismuth very often*in a metallic state. Oxyde of bismuth in a spoon before the blow pipe, melts to a brown glass. With microcosmic salt it forms a grey yellow glass; a further proportion of oxyde renders it opaque. With borax k forms a grey glass, which decripitates in the interior flame, and the metal is reduced and volatilized. It is easily re due ed on charcoal. ( 440 ) When bismuth is dissolved in diluted nitric acid, the solution is colourless; but if water be added, it will become turbid, and a white precipitate formed, which is the oxyde of bismuth. This oxyde is com- bined with water, and a small portion of nitric acid. The majistery of bismuth is the same oxyde, but containing, it is said, more of the subnitrate, which is produced by adding a larger quantity of water. Pearl white, another preparation of bismuth, is formed by decomposing the nitrate of bismuth writh carbonate of potash. It is said, however, that in oe- der to produce the pearly appearance, muriatic acid is added to the nitric solution before the addition of potash. The white oxyde of bismuth, when used as a me- dicine, should be entirely free from lead; but as it is blackened by sulphuretted hydrogen gas* like lead, it is obvious that this test will not distinguish between the two metals. To detect lead, let the oxyde be dissolved in acetic acid, and add to the solution sul- phate of soda ; if it be present, sulphate of lead will precipitate,'which may be examined in the usual manner. NATURAL AND ARTIFICIAL GEMS. The imitation of gems may be traced to a remote period, and has of late been brought to great perfec- tion. The idea of communicating a particular col- our to glass, in imitation of precious stones, was put into practice in the time of Pliny, who, besides oth- ( 441 ) ers, mentions artificial hyacinths, sapphires, and a black glass resembling our obsidian, which he calls gemma vitrae. That the art must have been in -ome respects perfect is evident from the deceptions which were practised with them. Tertulian ridi- cules the folly of paying as dear for coloured glass as for real pearls. The glass houses of Alexandria, were celebrated among the ancients for the skill and ingenuity ofthe workmen employed in them. An Egyptian priest made a present to the emperor Ad- rian of several glass cups which sparkled with col- ours of various kinds, and which, as costly wares, the emperor used only on grand festivals. Seneca men- tions one Democritus, who had discovered the art of making artificial emeralds. This, however, was said to be done by giving a green colour to quartz, or rock crystal. Porta, Neri, and some others have given direc- tions for colouring glass. Sundry discussions soon after took place as to who discovered, and applied certain colouring ingredients. The purple powder of Cassius was one of them. What is denominated paste, is a glass made in imitation of gems. The paste, however, is usually considered the base, which consists of silica, potash, borax, red oxyde of lead, and sometimes arsenic. Colourless quartz and bo- racic acid are likewise used. The glass should be well made, and the denser it is, the greater the beau- ty ofthe artificial stone. The colours are imparted by the following sub- Stances; for topaz, glass of antimony, Cassius' pur- ( 442 ) pie, and per oxyde of iron; ruby, oxyde of manga- nese ; emerald, green oxyde of copper and oxyde of chrome, or acetate of copper and per oxyde of iron 5 sapphire, oxyde of cobalt; amethyst, oxyde of man- ganese, oxyde of cobalt, purple of Cassius, or oxyde of manganese and oxyde of cobalt; beryl, glass of antimony, and oxyde of cobalt; syrian garnet, or ancient carbuncle, glass of antimony, Cassius purple, and oxyde of manganese, he.* Many other sub- stances have been used ; but these will give an idea ofthe colouring ingredients of glass, in the prepara- tion of gems; an art, which has of late years been brought to that perfection, as to produce artificial gems possessing all the physical characters ofthe re*- al stones, even to deceive the eye of the experien- ced jeweller. Some stones cannot be imitated, on account of the different colours in the same stone, the arrangement or distribution of those colours, &c. Thus agate, which is an aggregate of various silice- ous stones, as chalcedony, opal, carnelion, jaspar, he. is of this kind. The true precious stones have ufually silica for their bases, and, in general, are so remarkably hard as io scratch glass. All the vari- eties of quartz are infusible before the blow pipe j but with the compound blow pipe, a piece of rock crystal will melt into a white glass. An artificial *The following composition when fused, is said to imitate th* garnet very closely; Purest white glass, £ ounces. Glass of antimony 1 ounce. Powder of Cassius^ 1 grain. Manganese, \ do. ( 443 ) gem submitted to the blow pipe will soon melt— Quartz is fusible with a flux. Different colours may be given to quartz by heating it, and then plun- ging it into some metallic and vegetable solution. which possesses colour. The smoke of burning wood will impart a brown colour. Artificial gems are readily fusible before the blow pipe, as they are nothing more than coloured glas- ses, and are less hard than natural gems. Precious stones are, for the most part, infusible before the common blow pipe; and with respect to hardness. are generally superior to glass; hence they scratch glass. Neither the artificial nor the natural gems, provided they are composed of a due proportion of silica, are acted upon by acids, except the fluoric, which we know takes up the silica, and passes off in the state of silicated fluoric acid. If we are desirous of examining an artificial gem to ascertain its colour- ing ingredient, we may introduce into acrucibleone part of the gem and three parts of potash, and fuse them together. A compound of silica and potash will thus result, which is soluble in water, forming the silicated alkali. This fluid, and the insoluble part which which will subside, consisting ofthe me- tallic oxyde, he. may be treated by reagents.* * We have omitted the greater part of this article, consisting of I'-Z pages at least, on the chemical and physical characters of the, so called, precious stones; and although it was merely a summary of their properties in general, and in that respect in- teresting, yet we were obliged to omit it, to admit other articles, or to have swelled the work, as it is now much larger than we an- ticipated. ( 444 ) GOWLAND'S LOTION. We notice this cosmetic, not that we believe it al- together safe as a wash, especially when used in any quantity at a time, but that a spurious lotion is fre- quently sold as the genuine, which is prepared with arsenic in the place of corrosive sublimate. An ar- senical solution, although blended with the milk of almonds, and mixed with a dueproporton of sul- phate of zinc and acetate of lead, by which an ace- tate of zinc and a sulphate of lead are formed, as in the genuine lotion, must be more or less injurious to the skin. If arsenic, or arsenious acid be suspected, the fact may be known by adding to the filtered fluid the ammoniaret of copper, (ammoniated sulphate of cop- per of some,) when a yellowish green precipitate of arsenite of copper will be formed; or by adding hy- drosulphuret of ammonia, collecting the precipitate, and throwing it on ignited coals, and recognising the presence of arsenic by its garlic smell. See Arsenic. Genuine lotion should neither show a precipitate in the first instance, nor afford a precipitate which would give a garlic odour on hot coals. It is pre- pared by adding eight quarts of water to one pound of bitter almonds,* and forming an emulsion in the * There are two kinds of almonds, the sweet and the bitter.— The former are used for sweet emulsions and other purposes. Proust remarks that the emulsion may be curdled by heat, and that a whey is obtained from it, containing gum, extractive mat- ter, and sugar, and a curd, which yields oil by expression.— ( 445 ) usual manner ; then making a solution of eight oun- ces of acetate of lead, and eight ounces of sulphate of zinc, each in a quart of water ; and putting into pint bottles one ounce measure of each solution, eight grains of finely powdered corrosive sublimate, and as much water as will fill the bottles one half, adding for the other half the almond emulsion. The mix- ture when shaken is fit for use. This is the correct formulae for the once celebrated Gowland's lotion. MILK OF ROSES. While noticing cosmetics, we may remark, that When bitter almonds are expressed, an oil is obtained, and all the bitter matter remains in the cake, which is soluble in watery and spiritous menstrua. We mentioned, (see Hydrocyanic Acid,) that bitter almonds contain a deleterious principle. A water distilled from them, partakes also of the same proper- ties. Some are of opinion, as Mr. Nicholson, that the vegetable principle of bitterness in almonds, and the kernels of other fruits, is only destructive to animal life when separated from the oil and farinaceous matter. This principle, however, exists inde- pendently of oil, or farinaceous matter, and exerts its influence or power whether they be present or not, and is now known to be prussic acid. If bitter almonds, &c. containing this acid, be swallowed by mistake, the best remedy after emetics, is a com- bination of sulphate of iron with bicarbonate of potash. To birds in particular, bitter almonds are a fatal poison.— The eating of them was supposed to prevent the intoxicating effect of wine. We may add also, that they are frequently us- ed instead of apricot kernels in ratitia, and in the place ofthe lauro-cerasus in making counterfeit brandy, and also very im properly, by confectioners for flavouring sundry articles ! See Spiritous Liquors. 38 ( 446 ) this preparation, called the milk of roses, owes its peculiar consistence to the oil of almonds, in con- junction with potash, to which wax is occasionally joined. The cream or milk or roses is prepared by Chap- tal, by taking equal parts of rose water, spirit of wine a la rose, and spirit of sugar. He colours it with an infusion of cochineal. The common recipe is one ounce of sweet oil of almonds, three quarters of an ounce of a concentrat- ed solution of potash, one quart of water, and half a drachm each ofthe essential oils of lavender and ro- semary which are mixed together. The mixture as- sumes a milky or rather saponaceous appearance.— When a drachm of white wax is melted, and mixed with the oil of almonds, previously to the admixture with the other ingredients, the whiteness as well as the consistence is greatly increased. The milk of roses, improperly so called, has been extolled as a cosmetic, but without much cause. Genuine milk of roses should be white, have a thick consistence, and not separate on standing. The safest and best cosmetic we are acquainted with, is one which was recommended in the Pocket Conspectus many years ago, consisting of nothing more than the milk of sulphur (lacsulphuris,) mixed with a weak solution of acetate of lead, a prepara- tion we have found to remove cutaneous eruptions without difficulty, and is decidedly as effectual as so- lutions of sublimate. ( 447 ) EAU DE LUCE. There are several recipes recommended for the preparation of eau de luce, which is nothing more than the volatile alkali rendered more pungent by dif- ferent additions. The best formula?, however, appears to be by -nixing about 20 drops of the volatile oil of amber, with one ounce of alcohol, and twelve ounces of am- moniated spirits. A solution of soap in alcohol, add- ed to the oil of amber, and mixed with caustic am- monia (aqua ammonia puree,) is more frequently adopted. Good eau de luce, on standing, should not separ- ate, but preserve its milky appearance, and not lose ks pungency, or peculiar smell. Professor Beckman, (Hist. Invent, ii, 489,) speak- ing of eau de luce, remarks, that when of the best quality it always retains its milky colour, which is not the case when spirit of sal ammoniac (aqua ammonia carbonatis,) and oil of amber are mixed together. " As a soap," says Beckman, " it is employed to remove from cloth many spots which cannot be re- moved by common soap ; and it is fitter for this pur- pose as it very speedily evaporates. Mixed with water it is administered also for various diseases and accidents; such, for example, as the bite of some snakes ; and, in consequence of its strong smell, it acts, when held to the nostrils, as a powerful stimu- lant in cases of fainting. But it is requisite that those who use it for the latter purpose should know, ( .4.48 ) that a small drop of it, if it come in contact with the eye, would occasion blindness." Eau de luce was first made in Paris; but an apothecary at Lisle gave it a blue colour by means of copper, because, we arc told, he was not able to give it a milky appearance, and hence it received the name of blue eau de luce. Dossie (Elaboraiory laid open, printed at 1758,) published the formulae for making this preparation. Eau du luce, we remarked, in consequence of its pungency, is a powerful siimulant to the olfactory nerves; but the most common preparation for this purpose is what is commonly called the smelling salts, or sal volat, which is the concrete carbonate of ammonia. This is usually scented with the essence of lemon or of bergamot, and frequently eau de luce *s added. The salt of vinegar, as it is improperly called, is used for the same purpose. This prepar- ation consists chiefly of acetic acid, or radical vine- gar- We may remark here, that the offa alba Helmon- tii is likewise a preparation of ammonia : if one part of a saturated solution of carbonate of ammonia in water, be mixed with two parts of pure alcohol, a complete coagulation will take place, which is the offa alba of Helmont and Trommsdorf; and if the alcohol be previously coloured with cochineal, the coagulum will have the appearance of blood, which will liquify by the friction ofthe hand; hence the mystical ceremony in some of the Neapolitan and Greek churches, which is imposed on the people as the liquifaction ofthe blood of St. Johannes! ( 449 ) RED SAUNDERS. Saunders is a hard wood the produce of the pter^ ocarpus santalinus, a tree which grows on the Coro- mandel coast. The yellow or citrin saunders is a beautiful wood of the colour of lemon peel, and has a fragrant smell resembling a mixture of musk and roses. The white saunders as they are called, also possess a fragrant smell and aromatic taste. The red saunders is ofa dense and compact texture, remar- kably heavy and very hard. It is exported to Eu- rope in logs, the outer part of which is a dusky, and the inner of a blood red. It has but little smell and taste. The wood is at first light red, but becomes very dark by exposure to the air. It is used chiefly for colouring drugs. The colouring matter is of a resinous nature, and hence it is taken up by alcohol, but not by water. The alcoholic tincture is a fine red. Ground brazil wood has been sold for red saun- ders ; but the imposition is readily detected, as was first pointed out by Dr. Lewis, by the red saunders yielding no colouring matter, whereas Brazil wood will impart its colour almost immediately, a distinc- tion which cannot be mistaken. CIVET. Civet is a kind of perfume, which bears its name from the civet-cat, as it is obtained from the inguinal region of that animal. It is squeezed out of the ca- 38* ( 450 ) vity, where it is secreted every other day. Good civet is ofa clear, yellowish or brownish colour, neither fluid nor hard, but about the consistence of honey, and uniform throughout; of a very strong smell, quite offensive when undiluted, but agreeable when only a small portion of civet is mixed with a large one of other substances. With oils, both ex- pressed and distilled, it readily unites, but is not ac- ted upon by alcohol or water. The Italians make it an ingredient in perfumed oils, and thus obtain the whole of its scent. Oils dissolve the whole of it. It is very rare to meet with civet unadulterated. The substances usually mixed with it, are lard and but- ter ; it is almost impossible to distinguish the adul- teration, or discover it. MUSK. Musk is scented into a kind of bag situated in the umbilical region of the quadruped called moschus moschifer. The characters of musk are, that it is brownish red, feels unctuous, tastes bitter, and has an intense- ly strong aromatic smell. Musk, in consequence of its high price, is frequently impure. It- is par- tially soluble in water and in alcohol; the former acquires its smell, but the latter does not retain it * It is wholly soluble in nitric and sulphuric acids, but ihe odour is destroyed. When rubbed with potash or soda, it developes the odour of ammonia. Oils do not act upon it. Rectified spirit of wine ( 451 ) (alcohol) takes up the whole of the active part of musk. Dr. Parr, (Medical Dictionary, vol. 1, p, 1008,) assures us, that the tincture of musk, prepar- ed with alcohol, although of itself having no smell. will, in the quantity of a drop or two, communicate to a quart of water a rich scent; and that the quan- tity of water, which may thus be flavoured by a cer- tain known proportion of musk, he considers is the best criterion of its goodness. The best tnusk is brought from Tonquin in Chi- na, in thin bags, with brownish hairs; an inferior sort from the East Indies is in bags with white hairs. The best musk, besides the characters we have mentioned, when chewed or rubbed with a knife on paper, is bright, yellowish, smooth, and free from grittiness; and when laid on a red hot iron, will inflame, and burn almost entirely away, leaving only an exceedingly small quantity of light greyish ashes. Artificial musk is a pharmaceutical preparation made by pouring nitric acid on oil of amber. It has little ofthe odour of musk; it resembles more that of nitrous oxyde. EBONY. Hard, heavy, and compact wood, as the apple- tree, he. is frequently stained or dyed to resemble ebony, and often passed off assuch. The detection may be effected by a few experiments, which we shall notice. The true ebony is produced chiefly in the island ( 452 ) of Madagascar, and the Mauritius. It is an exceed- ingly hard and heavy kind of wood, susceptible of a very fine polish, and on that account used in masaic and inlaid work, for toys, fac. It is of differ- ent colours, most usually black : also red, and green ; the first is mostly preferred. The best is a jet black, free of veins and rind, very massive, astringent, and of an acid, pungent taste. It yields an agreeable perfume, when laid on burning coals; when green it readily takes fire. Green ebony is not confined to inlaid work, it has been used in dyeing. Of red ebony, called also Grenadilln, we know little more than the name. There is an ebony which comes from the West Indies; it is either white or black. It is a fine timber wood, has a smooth even grain, which takes a good polish, and is used principally by turners, although seldom, we believe, in this country. The heart is usually the complexion of jet. The bastard ebony, growing in the West In- dia islands, palled mountain ebony, which is a dark brown, is often employed for different purposes.— The specific gravity of real black ebony is 1.209. and the only woods which are heavier, are lignum vitas, (sp. gr. 1.333,) pomgranate, (sp. gr. 1.354,) and Dutch box, (sp. gr. 1.328,) whereas the others as beech, alder, maple, apple, pear, &c. are consid- erably less. Ebony, therefore, will sink in water, but the dyed woods made in imitation of it except from the woods that are heavier, will swim or float. The other descriptions of box wood are of a specif- ic gravity less than water, and hence will float. ( 453 ) Wood is dyed black, in-imitation of ebony, by the usual black dye, composed of green vitriol, logwood and galls. If a portion of this wood be cut in pieces, and digested in sulphuric acid very largely diluted, it will lose its black colour, and assume a yellowish red tinge ; and if the acid be examined for iron, previously neutralising it with alkali, by using either tincture of galls, or ferrocyanate of potash, the pre- sence of that metal will be shown. Diluted sulphur- ic acid digested in the same manner on real ebony, will have no effect ; the acid will not produce a black with galls, nor a blue with ferrocyanate of pot- ash. It is difficult, in imitative ebony, to dye the wood thoroughly through ; and, therefore, when cut the uniformity of colour will be wanting. Green e- bony, if imitated by dyeing wood with a solution of copper, a practice usually adapted for staining or dyeing of that colour, may be examined by digesting it in diluted sulphuric acid, saturating the acid with ammonia, and adding an excess of that alkali. The well known blue colour will appear. The same treatment with the genuine wood will give no indica- tions of copper. Green ebony, we are informed. imparts to alcohol a fine green colour ; this would not be the case with the dyed wood, if the colouring ingredient is of copper. The art of dyeing, and staining wood of different colours, has been much improved, since a variety of experiments have been made on that subject, a short ( 454 ) account of which may be seen in the Artisfs Man* nal. article Dyeing.* IVORY. A few remarks respecting this substance, which is intermediate between bone and horn, and is the tusk, or tooth of defence ofthe maleelephant,may be inter- esting in connection with our observations on ebony. The tusks weigh from 30 to 130 pounds; and when entire are of a yellowish brown colour on the outside, but white internally. The finest, whitest, and most compact, comes from the island of Ceylon. Hunting the male elephant at the Cape of Good Hope, as many of the hunters, are destroyed, meets with great encouragement; for every pound of ivo- ry they receive a guilder. The tooth of the sea horse, or rather the project- ing weapon of the sea-unicorn, furnishes a kind of ivory not of much use, since from their twisted form they cut to great disadvantage, and besides is too hard to be sawed or wrought like ivory. It is used for making artificial teeth. Ivory is not capable of being softened by fire; but is not altogether so hard and brittle as bone. It *Mr. Hall (Silliman's Journal iii, 166,) speaks ofa stain for some sorts of wood used in the making of cabinet furniture.— It consists of a decoction of walnut or hickory bark, with a small quantity of alum. Wood, of a white colour, receives a beauti- ful yellow tinge, very little liable to fade. He recommends it in particular for white maple, curly maple, and remarks that it gives the finest appearance to birds eye maple, a lustre even tt> the darkest shades. (, 455 ) is composed of gelatin 24, phosphate of lime 64, and carbonate of lime 0.1 in 100 parts. It is suscepti- ble of receiving a stain or dye like bone; hence is frequently coloured. The coal of ivory is the true ivory black. If pieces of ivory be put into a cruci- ble, the crucible filled with sand, and exposed to the action ofa strong heat, the ivory will be carbonized, and appear of a perfect black ; it is dense, and com- pact, and is readily recognised from the common bone-black. The principle uses of ivory are for making math- ematical instruments, boxes, combs, dice, and vari- ous ornamental utensils. When bone is substituted for ivory, which is fre- quently the case, it is easily recognised by its pores, which are not to be seen in ivory, and by its wanting beautiful white veins or marks by which ivory is distinguished. Ivory when boiled in the usual dye stuffs, as for example, cochineal, muriate of tin, and bitartrate of potash, for red or scarlet, becomes soft in the exte- rior, and reserves the colouring matter with ease. If digested in muriatic acid, it undergoes the same change as bone, though not so rapidly ; the phos- phate of lime will be taken up, and the gelatin re- main. TORTOISE SHELL, The plates or scales of the Hawk's-bill turtle (te's- tuda imbricata,) furnishes that beautifully variegated ( 456 ) and transparent substance called tortoise-shell. It differs from shells in its composition, and approach- es the niture of nail. Macerated in nitric acid, it gradually softens, and seems to be composed of mem- branes laid over each other, having the properties of coagulated albumen. When burnt, it yields phos- phate of lime and soda, with a little iron. When tortoise-shell is steeped in boiling Water, it is rendered soft, and is then capable of being mould- ed into almost any form. The ancient Greek and Romans were very partial to its use, if we may judge by their decorating with it doors, pillars, and even beds. At Rome its consumption was very great.— Velleius Paterculus informs us, that when the city of Alexandria was taken by Julius Caesar, the ware houses were so full of this article that he proposed to have made it the principal ornament of his tri- umph. Tortoise-shell has been imitated with success, al- though the eye can readily perceive the difference. For this purpose horn is first softened, and pressed into plates; a paste consisting of two parts of quick- lime, and 1 part of litharge, made into a proper con- sistence with soap lie, is applied, leaving those parts bare which are to be transparent. When thoroughly dry, remove the paste, and if the operation has been dexterously performed, the horn will appear varie- gated, or partly opaque and partly transparent. A great deal of art is required to produce very accu- rate imitations. ( 457 ) ROSES. We notice the rose in consequence of its prepara- tions being adulterated, as the oil or attar of roses. White roses are the weakest; but the damask, the rosa pallida, or centifoUa Lin. are the strongest in aroma and essential oil, and are, therefore, principal- ly used. Their odour is imparted to water and spir- it, but chiefly to the latter. On distilling large quan- tities, a small portion of fragrant butyraceous oil, of a yellowish colour, is obtained, which concretes in a slight degree of cold. Both the water and oil are chiefly used in perfumes. The red rose, rosa centifoUa, has but little of the fine flavour of the pale sort. They tinge water with a deep red colour, and spirit with a pale one. The extract from a watery infusion is austere and bitter; that from spirit, in a greater degree. Rose water is the petals of damask roses, the heels being cut off, distilled with water. The conserve of roses is the red roses gathered before the petals are unfolded, beat up in a mortar with sugar, in the proportion of one to two. Very frequently molasses is used in preparing this con- serve, and is sometimes added to soften it. Con- serve, containing molasses, is always unusually soft, and in summer becomes so thin as to run, and fre- quently to spoil by fermentation. The honey of roses is prepared from the pe- tals, which are infused in boiling water, then strain- ed,'and the infusion mixed and boiled with hone^ { 458 ) The sirup of roses is the petals macerated in boil- ing water, the infusion then strained and evaporated, and sugar added to it to form a sirup. The infusion of roses is merely an infusion of the petals in boiling water, slightly acidulated with sul- phuric acid, with the addition of a small portion of sugar. The attar or essential oil of roses, so highly es- teemed as a perfume, is usually prepared in India. Forty pounds of roses with their calyces, are put into a still with sixty pounds of water. The distillation is continued till 30 lbs. of water come over. This water is then poured upon 40 lbs. of roses, and 15 or 20 lbs. more are to be drawn off. It is then poured into tin pans, and exposed to the fresh air for the night. In the morning the attar will be found coag- ulated, and floating upon the surface of the water. The roses of India do not appear richer in oil than those of Europe or America. From two to three drachms of oil are procured from one hundred weight. Some have obtained half an ounce, some an ounce, and Hoffman has procured two ounces from the same quantity of leaves. It is adulterated sometimes with the oil of sandal wood ; but this oil does not congeal in common cold, and its peculiar smell predominates, sometimes with that of sweet grass. The latter imparts a green colour, and the oil does not easily congeal in a moderate tempera- ture. The colour is no criterion of its genuineness, since the real atter differs considerably in this res- pect. * ( 459 ) The alter of roses should be of a thick consist- ence, and even retain its solidity m warm weather. If adulterated with fixed oils, as oil of ben, olive oil, &c. and which is frequently the case, the fraud may be discovered like similar adulterations of essential oils, by exposing it to heat; the pure oil will evaporate, and leave the fixed oil. Besides, the attar will leave a stain on paper, after exposure to heat. The mire oil should evaporate entirely, without leaving any residue. Alcohol cannot be used for sophisticating it; it will merely take up a part, and the fluid will be liquid as water. If cheaper essential oils were used, they would change the odour of the oil, and render it at the same time thin. The attar of roses is an agreeable, but expensive perfume. We may also mention another sophistication, in order to render it solid, viz.: by melting white wax or spermaceti with the olive or other oil made use of; the presence of wax or spermaceti may be detected by evaporation. Having thus gone through the examination of dif- ferent substances, it may be useful to enumerate the reagents, which will be generally required in ex- perimental investigations concerning the detection of poisons, and of adulterations in general. The re- agents should be perfectly pure, and with the excep- tion of test papers and fluxes for the blow pipe, be preserved in well stoppered bottles. The bottles ma* ( 460 ) be conveniently put into a chest, with divisions be- tween them, and the chest furnished with a drawer for containing the test papers and some other dry substances. CHEMICAL REAGENTS. Sulphuric acid. Nitric acid. Muriatic acid. Dilute sulphuric acid, 1 acid 3 water. ------nitric acid, do ------ muriatic acid, do Nitro muriatic acid. Aqueous chlorine. ------~ sulphurous acid. -----r— sulphuretted hydrogen* Acetic acid. Phosphoric acid. Tartaric acid. Solution of potash. ■ soda. ■----------- ammonia. -------■---- carbonate of potash. ----------- carbonate of soda. ---- ■"' carbonate of ammonia. -------—— oxalic acid. ----------- oxalate of ammonia. ----------- barytes. ----------- acetate of barytes. ----------- nitrate of bary tes. --------■— muriate of barytes C 461 ) -----------phosphate of soda. -----------sulphate of silver. ----------■ muriate of tin. -----------muriate of platinum. -----------muriate of gold. -----------per chloride of mercury, -----------muriate of ammonia. -----------nitrate of lead. -------—■— nitrate of mercury. ----------- iodine in alcohol. -----------nitrate of silver. ------>---- ferrocyanate of potash. -----------muriate of lime. ----------- hydrosulphuret of ammonia, ----------- hydriodate of potash. ■■ soap in alcohol. -----------acetate of silver. -----------chromate of potash. ----------- ammoniaret of copper. -----------sulphate of soda. -------•— arsenious acid. ----- acetate of lead. —.--------succinate of ammonia Tincture of galls. Alcohol. Chlorate of potash. Nitrate of ammonia. Test papers, litmus. __________do reddened by acid _____----turmeric. . — brazil wood. 38* f 462 > Black flux. White flux. Microcosmic salt. Cylinders, or plates of copper. --------------------tin. --------------------zinc. ■ iron. OCCASIONAL REAGENTS Deu'to-acetate of iron. Tincture of ginger. Iodide of starch. Oil of turpentine. Solution of gelatin. Dry caustic potash. Albumen. Arsenite of potash. Hahneman's wine test. Benzoate of soda. ---------of ammonia. Silicated potash. Tannin. Nitrate of potash. Aqueous carbonic acid. Muriate of soda. Supersulphate of alumina and potash. Subacetate of lead. Protosulphate of iron. Infusion of galls. Infusion of cabbage. ( 463 ) Professor Brande in his Manual of Chemistry, has given an engraving of a portable laboratory for die analysis of mineral waters, which may be useful to the experimental enquirer. It consists of a tray sufficiently large to hold the apparatus which he mentions ; and in which is placed, at one end, but . raised from the tray, an open box containing the bot- tles, arranged in the same manner as in a chest.— This arrangement is convenient. The tray should contain the following articles : Florence flasks. Wedgwood and glass basins. Platinum and silver crucibles. Silver capsule. Funnels. Test-glasses and test-tubes- Glass rods. Filtering paper. A spirit and an argand lamp. A retort and receiver. -Copper basin to serve as a sand bath. Blow pipe. Thermometer. Dr. Wallaston's scale of equivalents. Dropping bottle. Watch glasses. A support for holding glasses over a lamp. A small brass stand with rings. A tube, with a bulb in the centre and pointed ex- iremity, for drawing up small portions of liquids. { 464 ) .' ^Platinum pincers. A small, but good balance, with well adjusted weights, accompanied by a phial and counterpoise for taking specific gravities. 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