SUGAR OF MILK. 183 



If we add ammonia to the soluble compound, the insoluble 

 compound, noticed above, falls down. If we digest it for a long 

 time with an excess of oxide of lead we obtain a subsalt compos- 

 ed of, 



Sugar of milk, . 12-55 or 8- 



Oxide of lead, 87-45 or 55-74 = 14 x 4 



100.00 



Sugar of milk was first subjected to an ultimate analysis by 

 Gay-Lussac and Thenard.* Berzelius analyzed it in 1815,f 

 Prout in 1827,J Liebig in 1834, and Brunner in 1835.|| The 

 following table exhibits the result of these analyses : 



and y Th" S nard Berzelius - Prout. Liebig. Brunner. Mean. 



Carbon, 38-825 39474 40.00 3951 40-437 39-649 



Hydrogen, 7-341 7-167 6-66 6-74 6-7J1 6-926 



Oxygen, 53-834 53-359 53-33 53.75 52-852 53.425 



100-000 100-000 100-00 10000 100-000 100-000 

 These experiments exhibit the constitution of sugar of milk in 

 crystals. They lead to the formula, 



12 atoms carbon = 9 or per cent. 40 

 12 atoms hydrogen = 1-5 ... 6-66 



12 atoms oxygen =12-0 ... 53-33 



22-5 100-00 



But, according to Berzelius, 100 parts of crystals of sugar of 

 milk when dried at 212, or when combied with oxide of lead, 

 lose 12 of water. Hence 22-5 would lose 2-7 of water or 2J 

 atoms. Let us suppose the loss to be only 2.25 or two atoms 

 water, then it would follow that anhydrous sugar of milk is com- 

 posed of, 



12 atoms carbon, 9 or per cent. 44-44 

 10 atoms hydrogen, = 1-25 ... 6-18 



10 atoms oxygen, = 10- ...49-38 



20-25 100-00 



This is precisely the constitution of anhydrous cane sugar. Yet 

 the properties of the two differ exceedingly from each other. 



* Recherches Physico-Chimiques, ii. 295. 



t Annals of Philosophy, v. 266. J Phil. Trans. 1827, p. 383. 



Annalen der Pharmacie, ix. 24. || Poggendorf a Annak M, xxxiv. 335. 



