GLYCEROL. 17 



to preserve its strength) glyceryl tri-nitrate (nitro -glycerine), 

 usually mixed with small quantities of di- and mono -nitrates, is 

 formed. This is a heavy explosive liquid of specific gravity 

 1-6 and of limited solubility in water. This compound is best 

 known as a powerful explosive. 



With strong sulphuric and phosphoric acids glyceryl mono- 

 hydrogen sulphate and mono-glyceryl di-hydrogen phosphate or 

 glycero -phosphoric acid are produced. These have the com- 

 position 



S0 2 (OH)OC 3 H 6 (OH) 2 and 

 PO(OH) 2 OC 3 H 6 (OH) 2 respectively. 



Two glycero -phosphoric acids (a and ft] are known, and are 

 most easily prepared (as sodium salts) by Poulenc's process ; 

 a mixed sodium di-glyceryl phosphate is produced by heating 

 glycerol with sodium di-hydrogen phosphate, and a mixture of 

 a- and ft- di-sodium glyceryl phosphates is obtained by alkaline 

 hydrolysis. The salts of the /?-acid are less soluble and more 

 readily crystallise than those of the a-acid. 



When glycerol is heated with alkalies above 250 C. various 

 products are formed ; among these are formic, acetic, acrylic, 

 and lactic acids. The oxygen of the air seems to play an 

 important part in these changes, as all the products contain 

 more oxygen and less hydrogen. No change takes place below 

 250, especially in the absence of air. 



Several glyceroxides are known i.e., bodies in which the 

 hydrogen of the hydroxyl groups is replaced by metals. By 

 heating lead oxide with glycerol, lead glyceroxide is formed. 

 Glycerol also dissolves lead oxide. 



By treating glycerol with sodium dissolved in alcohol a crys- 

 talline deposit of the composition C 3 H 7 Na0 3 , CgHgO is formed, 

 which, when heated at 100 in a current of hydrogen, loses 

 alcohol. It is a white amorphous powder, very hygroscopic 

 and immediately decomposed by water. Calcium, strontium, 

 and barium hydroxides are freely soluble in glycerol, and 

 form glyceroxides, which may be dissolved in water ; the 

 aqueous solutions do not give precipitates with carbonic 

 anhydride. 



By the action of hydrochloric and hydrobromic acids, mono- 

 and dichlor-hydrin and mono- and dibrom-hydrin are produced. 

 There are two possible mono-chlor- and mono-brom-hydrins : 

 thus 



CH 2 C1 CH 2 (OH) 



CHOH and CHC1 

 CH 2 (OH) CH 2 (OH) 



