48 INTRODUCTORY — THE COISISTITUENTS OP MILK. 



products, of which acrolein (CgH^O) is the most important, are 

 given off. Di- and tri-glyoeric alcohols are also formed. 



By the action of acid oxidising agents — e.g., chromic acid and 

 potassium permanganate in acid solution — it is wholly converted 

 into carbon dioxide and water. Alkaline permanganate converts 

 it quantitatively into oxalic acid. By the action of bromine in 

 the cold glycerose is formed, which is an aldehyde ; by further 

 oxidation with bromine at a high temperature, or by boiling with 



CH2OH 



I 

 dilute nitric acid, glyceric acid C'HOH is produced. 



COOH 

 CUOH 



Tartronic acid CHOH is. under certain conditions, also 

 I 

 COOH 



produced together with glycolic, glyoxylic. oxalic, and formic 

 acids. 



Glyceric acid appears to have a constitution similar to lactic 

 acid (q.v.), from which it differs only by containing the group 

 CHo(OH) in place of CH.,. It forms a lactone and a dehydro- 

 derivative, and contains an asymmetric carbon atom. 



By the action of fuming nitric acid (mixed with sulphuric acid 

 to preserve its strength) glyceryl tri-nitrate (nit]'o-glycerine), 

 usually mixed 1 with small c^uantities 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 are 

 produced. These have the composition — 



S02(OH)OC.jH,(OH)2 and 

 P0(0H)20C,H,(0H)„ respectively. 



When glycerol is heated with alkalies above 250° C. a variety 

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

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

 tant 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. 



