ORGANIC ELEMENTS. 55 



sugar, and approaches nearer to the sugar of grapes glucose than 

 to that of the cane. It is obtained in an irregularly crystalline mass, 

 by evaporating diabetic urine to the consistence of syrup, and keeping 

 it in a warm place for several days. It is purified by washing in cold, 

 or at the most gently heated alcohol, till the liquor comes off colour- 

 less ; and then dissolving it in hot alcohol. By repeated crystallization 

 it is thus rendered pure. 1 In the notes of two cases of diabetes mel- 

 litus now before the author, it appears, that sixteen ounces of the urine 

 of one patient, of the specific gravity of 1-034, afforded a straw-co- 

 loured extract, which, when cold and consolidated, weighed one ounce 

 and five drachms. The same quantity of the urine of the other patient, 

 specific gravity 1'040, yielded one ounce and seven drachms. Neither 

 extract appeared to contain urea when nitric acid was added ; but when 

 a portion was dissolved in water, and subjected to a temperature of 

 212, traces of ammonia were manifested on the vapour being presented 

 to the fumes of chlorohydric acid. From this a conclusion was drawn, 

 that urea was present, as it is the only known animal matter decom- 

 posed by the heat of boiling water. In a little more than a month, 

 the subject of the latter case passed about four hundred and eighty 

 pints of urine, or about seventy-five pounds troy of diabetic sugar ! 



9. Bilin or Picromel. M. Thenard 2 discovered this principle in the 

 bile of the ox, sheep, dog, cat, and several birds ; Chevalier, in that of 

 man. To obtain it, the acetate of lead of commerce must be added to 

 bile until there is no longer any precipitate. By this means, the yellow 

 matter of the bile and the whole of the fatty matter are thrown down, 

 united with the oxide of lead ; the phosphoric acid of the phosphate of 

 soda, and the sulphuric acid of the sulphate of soda, are likewise precipi- 

 tated. The picromel may then be thrown down from the filtered liquor 

 by the subacetate of lead. The precipitate, which is a combination of 

 picromel with oxide of lead, must now be washed and dissolved in acetic 

 acid. Through this solution, sulphuretted hydrogen is passed to sepa- 

 rate the lead ; the solution is then filtered, and the acetic acid driven 

 off by evaporation. 



Pure picromel is devoid of colour, and has the same appearance and 

 consistence as thick turpentine. Its taste is at first acrid and bitter, 

 but afterwards sweet. Its smell, is nauseous, and specific gravity greater 

 than that of water. When digested with resin of bile, a portion of 

 the latter is dissolved, and a solution obtained, which has a bitter and 

 a sweet taste, and yields a precipitate with the subacetate of lead and 

 the stronger acids. This is the compound that causes the peculiar taste 

 of the bile. 



10. Cholesterin. This is a constituent principle of the blood, bile, 

 medullary neurine, and vernix caseosa. It is often precipitated from 

 bile in a crystalline state; and forms of itself concretions which have 

 an evidently laminated texture. It has been very frequently met with 

 in morbid secretions and tissues ; in the fluid of dropsies ; in that of 

 cysts and hydatids ; and in medullary fungus and other tumours. At 



1 Prout, Medico Chirurg. Transact., viii. 538. 



3 Memoir. d'Arcueil, i. 23, and Traite de Chimie, torn. iii. 



