296 CHEMISTRY. 



exi)losion, leaving spangles of metallic silver mixed with an amorphous 

 powder of autimouous oxide. It contained 26.30 per cent, of silver. — 

 {Am. J. Sci., Ill, xix, 393, May, 1880.) 



Grimaux and Adam have succeeded in effecting the synthesis of citric 

 acid from glycerin. Since glycerin is tri-hydroxyl-propane and citric 

 acid is hydroxyl-tri-carboxyl-propane, the theoretical conversion of the 

 former into the latter requires only the substitution of three carboxyls 

 for two hydroxyls and one hydrogen. Practically, this replacement 

 was effected in several stages: first, by the action of hydrochloric i^cid 

 on glycerin, dichlorhydrin, or hydroxyl-dichlor-propane, was produced. 

 By chromic acid this was oxidized to dichloracetone or oxydichlor- 

 propane. This, by the action of concentrated hydrocyanic acid, gave 

 dichloracetone- cyanhydriu, or hydroxyl-cyan-dichlor-piopane. By sa- 

 ponifying with hydrochloric acid, the corresponding acid hydroxyl- 

 carboxyl-dichlor-proi)ane was obtained. The sodium salt of this was 

 treated with j)otassium cyanide, giving hydroxyl-carboxyl-dicyan-i^ro- 

 j)ane. And this, when saponified as before, gave hydroxyl-tricarboxyl- 

 jjropane, or citric acid, identical in all its properties with that obtained 

 from lemons. Since glycerin can be made from trichlorhydrin, which 

 may be made by the action of chlorine on propylene, and since propy- 

 lene can be made from marsh gas and carbouous oxide, marsh gas itself 

 being i)roducible from carbon and hydrogen, the synthesis is complete 

 from the simple elements up to citric acid. — {Nature, xxii, 585, October, 

 1880.) 



Eosenstiehl has given the processes by which Baeyer has succeeded 

 in synthesizing indigotin, the coloring matter of indigo. Two of these 

 are described, in both of which cinnamic acid is taken as the point of 

 departure. On nitration, this acid yields orthonitro-cinnamic acid ; and 

 this is converted {a) into orthonitro-phenyl-propiolic acid by bromi- 

 nating and subsequently saponifying; or {b) into orthonitro-phenyl- 

 oxyacrylic acid by treatment with hyj)ochlorous acid and subsequent 

 saponification. The action of heat alone converts this latter acid into 

 indigotin, a temj)erature of 110° 0. being sufficient. But the action is 

 complex and the yield is small. Orthonitro-phenyl-j)ropiolic acid is con- 

 verted into indigotin by heating it with a mixture of alkali carbonate 

 and glucose, to 110° C. The action is regular, the indigotin separates 

 in the crystalline form, and the process has the very great commercial 

 advantage that the coloring matter can be developed directly on the 

 cloth. The mixture of the acid with the alkali and glucose being 

 printed on the cloth, exposure to superheated steam develops the color 

 fixed in the fiber. — {Ann. Chim. Fhys., xxi, 286, October, 1880.) 



Spiller has devised a simple means of identifying the coal-tar colors, 

 founded on the action of sulphuric acid on the dyeing material taken in 

 conjunction with the shades produced on and the tendency to dye silk, 

 wool, or cotton. The most striking reactions are as follows : Magdala 

 red with suli^huric acid gives a blue-black; saffranin a grass-green, be- 



