GLYCEKIN. 171 



Tribromhydrine (Tribromallyl), CWBr 3 . Is also 

 formed by bringing allyl iodide or bromide together 

 with bromine. Colorless, lustrous prisms ; fusing point, 

 16; boiling point, 219-220. When heated with 

 potassium cyanide and alcohol, it is converted into 

 tricyanhydrine (tricyanallyl) C 3 H 5 (C]N") 3 . , 



Hydriodic acid and phosphorus iodide convert gly- 

 cerin into allyl iodide and pseudopropyl iodide (p. 66). 



t QTT 



Glycerindisulphuric acid, C 3 H 5 <| ,gQ 2 Q 2 The 



potassium salt is obtained by heating dichlorhydrine 

 with a concentrated solution of potassium sulphite. 

 The free acid is a deliquescent syrup. Its salts crys- 

 tallize well. 



Glycerintrisulphuric acid, C 3 IP(S0 2 .OH) 3 . Is 

 obtained from trichlorhydrine, like the previous acid. 

 Tribasic. 



( (OTL\ 2 

 Glycerinsulphuric acid, C 3 H 5 j g g( j 2 Q H Is 



formed by mixing glycerin and concentrated sul- 

 phuric acid. Very easily decomposed. Monobasic 

 acid. 



The sulphur compounds, analogous to mercaptan, 

 monothioglycerin C 3 H 8 2 S, dithioglycerin C 3 H 8 OS 2 , and 

 trithioglycerin C 3 H 8 S 3 , are produced by the action of 

 potassium sulphydrate on mono-, di-, and trichlorhy- 

 drine. They are viscid bodies, very slightly soluble in 

 water, more easily in alcohol. They combine with 

 metals like mercaptan. 



Compound ethers. Glycerin nitrate (Nitro- 

 glycerin). C 3 H 5 (O.N0 2 ) 3 . Glycerin is added drop 

 by drop to a mixture of concentrated nitric and sul- 

 phuric acids immersed in a freezing mixture, and the 

 mixture afterward poured into water. Colorless oil, 

 heavier than water, and insoluble in it. Exceeedingly 

 explosive and poisonous. 



^ Fats. The fats, which occur in nature, are par- 

 tially solid (tallow, lard) and partially liquid bodies 



