102 



CHEMISTRY. 



sulphur, or sulphureted hydrogen, or even by 

 sulphurous acid, though, in a single experiment 

 in which sulphurous acid, evolved from copper 

 clippings, was passed into dilute nitric acid 

 (sp. gr. 1.15) for a couple of hours, no ammonia 

 could be detected in the liquid. The experi- 

 ment of Schonbein, moreover, is to be remem- 

 bered, in which ammonia, as well as sulphur- 

 ous and sulphuric acids, was detected in water 

 above which sulphur had been burned in the 

 air. It would seem to be plain, however, that 

 the substances previously mentioned must 

 usually be the most efficient agents for the 

 production of the ammonia." 



Being thus a common contaminant of sul- 

 phuric acid, the question occurred to Prof. 

 Storer, whether, in spite of its tendency to 

 change to nitrous and nitric acid through oxi- 

 dation, ammonia might not occur in a great 

 variety of the chemicals in whose preparation 

 sulphuric acid is used. To answer this, he 

 caused to be tested a considerable number of 

 the more important chemicals in common use, 

 and in the manufacture of which this acid plays 

 a part. Of these a list (too long for reproduc- 

 tion here) is given, with the proportions of 

 ammonia found in each. Of some 30 sub- 

 stances comprised in this table over two-thirds 

 contained ammonia, in some cases in note- 

 worthy quantities. 



On the point as to whether this ammonia 

 found its way into the substances examined 

 during the process of manufacture, or subse- 

 quently, Prof. Storer writes: "It is hardly 

 necessary to urge that the utmost care has 

 been exercised in these respects in all the fore- 

 going tests. A large proportion of the sub- 

 stances tested were taken from the tightly 

 closed, particularly well-ground, glass-stop- 

 pered bottles, in which they had been im- 

 ported, and which had never been opened un- 

 til the time of applying the test, but it is note- 

 worthy that this precaution seemed to be de- 

 void of significance. 



" Those substances, such as sulphate of soda 

 for example, which contained no ammonia 

 when taken from freshly-opened bottles, like- 

 wise contained none when taken from bottles 

 that had been frequently opened and which 

 had stood in a storeroom with other chemicals 

 during three or four years. I find, naturally 

 enough, that filter -paper and other porous 

 materials that have been exposed to the air of 

 a laboratory are highly charged with ammonia, 

 in the same way that the reagent bottles upon 

 our shelves become coated with ammonium 

 compounds, but it would seem, nevertheless, 

 that there is a limit to the penetrative power 

 of the ammoniacal gases. It will be noticed 

 for that matter that a tolerably large propor- 

 tion of the substances examined contained no 

 ammonia whatsoever, and in general I have not 

 observed that chemicals taken from their bot- 

 tles at the moment of reaching the laboratory 

 are any more liable to be free from ammonia 

 than those which have been long in store." 



Properties and Applications of Eosin. De- 

 pierre, in a note on the application of eosin 

 (translated in the American Chemist), details* 

 the various reactions concerned in the produc- 

 tion of this new dye-stutf, which is a potassa 

 salt of an acid belonging to the series of com- 

 pounds discovered by Baeyer. 



This chemist has demonstrated that phthalic acid, 

 combined with the divers phenols, yields com- 

 pounds phthaleins the production being effected 

 with elimination of a molecule of water. 



Ordinary phenol, pyrogallic acid, pyrocatechin, 

 resorcin, etc., yield phthaleins. Other acids analo- 

 gous to phthalic acid, e. g., mellitic acid, oxalic acid, 

 yield combinations analogous to the phthaleins. 



Kesorcin, obtained by treating asafcetida with 

 caustic soda, gives fluorescein, by combining with 

 phthalic acid 

 2(C la H 8 4 ) + C, 6 H 4 8 = C 40 H 12 10 + (H0) 4 . 



Resorcin. + Pbtbalic acid. = Fluoruscein. + Water. 



Hydrogenizing agents fix four equivalents of hy- 

 drogen and transform it into fluorescein, C 4 oH 16 Oj . 



If, to a solution of fluorescein in crystallizable 

 acetic acid, are added a few drops of bromine, im- 

 mediately this body is fixed, and from this liquid 

 water precipitates a reddish substance, which dis- 

 solves m alkalies with a characteristic yellowish-red 

 color. This derivative is the tetra-bromide of fluo- 

 rescein, C 40 H 8 Br 4 O 10 , which, when combined with 

 potassa, forms eosin, the formula of which is 

 C 40 H 6 Br 4 K 3 0, . 



Eosin forms a reddish-brown powder of metallic 

 lustre. On evaporating the aqueous solution, a sub- 

 stance, identical in appearance with uncrystallized 

 fuchsin, is obtained. The aqueous solution is re- 

 markably fluorescent, of yellowish-rose color by 

 transmitted light and green by reflected light. 



Concerning the physical and chemical properties 

 of eosin, this author states that it is soluble in 

 water, methylic and ethylic alcohol, in the alkalies, 

 alkaline carbonates, glycerin, and soaps ; it is in- 

 soluble in ether, phenic acid, anilin oil ; benzin. 

 Its solubility in water is very great. Fuchsin, which 

 is very soluble in water, requires 52 parts of cold 

 water and 6 of boiling water i. e., 1,000 parts of cold 

 water dissolve 19.2 of fuchsin, and 1,000 parts of 

 boiling water dissolve 166 parts of fuchsin. Eosin 

 requires 2.6 of cold water and 2.2 of boiling water 

 i. e., 1,000 parts of cold water dissolve nearly 400 

 parts of eosin, and 1,000 parts of boiling water 454 

 parts of eosin ; a boiling aqueous solution gives off 

 an odor of bromin. It is less soluble in commer- 

 cial alcohol than fuchsin ; this dissolves in 8.5 parts 

 of cold alcohol, while 11 parts are required to dis- 

 solve 1 part of eosin. 



Its coloring power is very considerable ; .004 

 gramme per litre gives a beautiful rose- colored 

 solution; with .001 gramme the solution is slightly 

 colored, and the dichroism is still sensible ; .000001 

 gramme still gives a rose-color under a thickness 

 of some centimetres. Eosin is decomposed by 

 most acids which precipitate a reddish-orange, 

 flaky substance, especially in concentrated solutions. 

 Acetic acid decomposes it also, but the solution re- 

 mains rose-colored, the acid of eosin being sliuhtly 

 soluble in acetic acid. Nearly all the soluble salts 

 with metallic bases yield lakes, the most brilliant of 

 which are those of tin, aluminium, and lead base, 

 and are all of a beautiful red. Zinc gives a yellow 

 precipitate : silver and mercury give violet lakes, 

 copper a brownish-red lake. An aqueous solution 

 of this coloring-matter dyes silk and wool and all 

 animal matter. The cold dye gives better shades 

 than the warm. This body, which, from the moment 

 of its appearance, was sold at the rate of 1,000 francs 

 pet kilogramme, and at present for 220 francs, yields 

 rote and gold colors of great beauty. And, in spita 



