94 



CHEMISTRY. 



surface to which it is but loosely attached, and con- 

 taminate the atmosphere to such a degree as to pro- 

 duce, by slow but continuous absorption, unmistak- 

 able symptoms of injury ? There will be those who, 

 through incredulity or from motives of interest, will 

 cite cases of perfect immunity under such conditions, 

 and will maintain that the brilliant color is inert, 

 even granting the presence of arsenic, and that there 

 is nothing in the paper-hangings in question to 

 arouse alarm or suspicion. The alleged cases of ill- 

 IK->S from this cause ought rather, they say, to be at- 

 tributed to bad ventilation and other abuses. Never- 

 theless, when the many-recorded and well-authen- 

 ticated instances of impaired health, including a 

 considerable number which have terminated fatally, 

 are examined impartially, little room is left for scep- 

 ticism. The cases are top numerous and too un- 

 equivocal to be thrown aside, and constitute a mass 

 of evidence which cannot well be refuted. It will be 

 unnecessary to cite a great number of these cases 

 here. The columns of the medical and of the gener- 

 al press of the last ten years contain the histories of 

 numerous instances. 



He then cites a few of the latest or most re- 

 markable cases, in which the arsenical wall- 

 paper caused serious injury to the health of 

 persons. Each case was thoroughly inves- 

 tigated, and no room was left for doubt that 

 the arsenic had done the mischief. Upon 

 removing the paper, or changing the apart- 

 ment, the evil symptoms ceased to be mani- 

 fested. All green paper-hangings are not ne- 

 cessarily poisonous; some may derive their 

 color from other pigments than the arsenite of 

 copper ; only the chemist's tests can determine 

 which of the papers contain arsenic. 



Mr. J. Wallace Young, of Glasgow, referring 

 to Dr. Draper's paper, writes to Nature con- 

 cerning some pigments other than greens 

 which contain arsenic. He says : 



The pigments were of French manufacture, and 

 said to be used in calico-printing, and were sent here 

 for trial, and rejected for two reasons : 1. Because 

 of the large quantity of arsenious oxide present ; 2. 

 Because colors equally good could be obtained on 

 calico by other methods, without the use of that 

 dangerous substance and at less expense. The 

 names were as follows : 



Bright scarlet pigment. Contained alumina, ar- 

 Benious oxide, arid aurine. 



Scarlet ponceau. Contained carbonate of lime in 

 addition to above ingredients. 



Dark green. A preparation of aniline green and 

 arsenious oxide. 



Chocolate and catechu pigment. Both contained 

 arsenious oxide. 



Now, as these lakes were very brilliant, I have no 

 doubt they would be found suitable for paper-hang- 

 ings. The arsenious oxide is not at all necessary for 

 the production of the lake ; but is used, I believe, 

 solely for the purpose of giving body to the pigment. 



My object in writing is, to warn chemists of the 

 necessity of examining for arsenic the bright scarlets, 

 reds, and other pigments found in paper-hangings, 

 as well as the greens. 



Test for Alum in Bread. The 

 Chemical News of May 17th contains a com- 

 munication from Mr. John Horsley, giving his 

 process of detecting the presence of alum in 

 bread. He makes a tincture of logwood by 

 digesting for eighthours two drachms of fresh- 

 ly-cut logwood-chips in five ounces of methy- 

 lated spirit in a wide-mouthed vial and filters 



it. Then he makes a saturated solution of 

 carbonate of ammonia in distilled water. A 

 teaspoonful of each solution mixed with a 

 wineglassful of water in a white-ware dish 

 forms a pink-colored liquid. Bread containing 

 alum immersed in this for five minutes or 

 so, and placed upon a plate to drain, will, in 

 an hour or two, go blue on drying; but, if no 

 alum is present, the pink color fades away. If, 

 on drying, a greenish tinge appears, that is an 

 indication of copper, as carbonate of ammonia 

 produces that color, but never a blue. 



As a counter-check for iron, a piece of moist blue- 

 colored bread may be drenched with a few drops of 

 glacial acetic acid, when that containing iron is 

 bleached of a dirty-white color, but with alum a rose- 

 pink or slight buff color will be observed. Or it may 

 be tried another way, thus : Take a piece of the bread 

 in its plain state, and, having digested it in dilute 

 acetic acid for an hour or so, press out the liquor and 

 filter; then put in a lump of carbonate of ammonia, 

 and, when all effervescence ceases, add to the clear 

 liquor a few drops of solution of sulphide of potassium 

 or sodium. If iron is present it will be indicated by 

 a dark colorj there being; no color produced with alum ; 

 but the addition of a little tincture of logwood im- 

 mediately reveals it. The alumina maybe estimated 

 quantitatively thus : Take, say, one- quarter of a 

 pound of crumb-bread, digest it in a clean basin with 

 some dilute acetic acid, arid allow it to stand a few 

 hours ; then break up the mass and pass the liquor 

 through a glass percolator, the rim being covered 

 with calico, repeating the percolation two or three 

 times till the liquor is clear. Throw in a lump of 

 carbonate of ammonia to saturation, and add tinc- 

 ture of logwood in excess, when, if alum is present, 

 a dark-blue color will be produced, with a flocculent 

 blue precipitate on standing a while. Collect this pre- 

 cipitate on a filter, wash it off into a dish with dilute 

 nitric acid, and evaporate the red liquor to dryness. 

 Collect the residue in a small Berlin crucible and 

 ignite it at a red heat, when a white powder will be 

 obtained consisting of alumina, with possibly a little 

 lime ; treat this with liquor potaseas, to dissolve out 

 the alumina, mix with a little water, filter, and boil 

 with carbonate of ammonia to obtain the pure alu- 



Aniline Colors. Of aniline black, M. Ehe- 

 uieck declares that a swatch of cotton dyed 

 faintly black with that article, forms a good 

 test for acids and alkalies, and can be used 

 alternately for either without losing its col- 

 or. If colored green by an acid and washed 

 in distilled water, it may be blackened again 

 by a very faintly alkaline liquid, such as com- 

 mon spring-water. He has analyzed the ani- 

 line black known in commerce as lucas black. 

 The sample was a black paste, formed by the 

 drying up of a liquid. On filtering and washing 

 the powder, there remained, evidently, muriate 

 of nigraniline. In the filtrate and washings 

 were found ammonia, iron, copper, lime, and 

 a little aniline. The liquor was dark and acid. 

 Its acidity is due to hydrochloric (muriatic) 

 acid, with a trace only of sulphuric. The mix- 

 ture is therefore probably muriate of aniline, 

 chloride of copper, chloride of iron, and chlo- 

 ride of calcium. In consequence of this great 

 acidity it damages the fibre, and, a large part 

 of the material being already combined, the 

 result is deficient in body. The hydrochloric 



