17B III. COMPOUND COMBUSTIBLES — 



and exported to the French sugar islands, to clarify the cane 

 juice. 



Deied white of egg, Albumen* The white of egg alone 

 dried, used to form a test liquor. 



Cuttle fish ink, Sepia. When fresh taken from the cuttle 

 fish, is a black glairy liquid, of a viscid consistence, a peculiar 

 fishy smell, and very little taste ; is preserved for use by being 

 spread round saucers, so as to dry before putrefaction commences, 

 or by evaporation on plates by a very gentle heat, or by being 

 inclosed in an exhausted receiver with oil of vitriol : used for 

 writing ink, and for a paint, much superior in ease of working to 

 Indian ink, which latter dries so quickly, that it is difficult to 

 colour a large pale shadow with it, and when once dry, some part 

 always adheres to the paper, and cannot be removed ; whereas 

 cuttlefish ink may be washed almost clear off. 



Melaina. Mix cuttlefish ink with very dilute nitric acid, 

 and keep it warm until it becomes yellowish, then wash the pow- 

 der well at first with water slightly alkalised with subcarb. of 

 potash, and afterwards with plain cold water. Melaina is taste- 

 less, black, powdery, insoluble in cold water, but soluble in hot 

 water; used as a pigment, superior to Indian ink. 



Human urine, Urijia hominis, P, SiciL Aperient ; used in 

 jaundice, ^j to ij, omni mane. 



Dried goats'' blood, Sanguis hirci siccatus. Sudorific, anti- 

 pleuritic. — Hoc/ s blood. Eaten with oatmeal. — Sheep's blood; — 

 Ox blood. Also eaten, and used instead of eggs to clarify liquids. 

 — Dried blood. Neat cattle or sheep's blood, dried by a gentle 

 heat, regulated by water baths placed one within another, so as 

 not to be coagulated: exported for clarifying sugar-cane juice. 



Urea. This substance in its purest form is exhibited in the 

 form of elongated, brilliant pearly scales ; it is colourless, trans- 

 parent, of a cool and sharp taste, and has an odour similar to that 

 of urine. According to M. Thenard, the following is the best 

 mode of obtaining it : urine evaporated to the consistence of a 

 syrup, is to be treated with its own volume of nitric acid at 24 

 deg. ; the mixture is to be shaken and immersed in an ice-bath 

 to solidify the crystals of supernitrate of urea ; these are washed 

 with water at 0, drained and pressed between sheets of blotting 

 paper. When they are thus separated from foreign matters, they 

 are to be dissolved in water, to which subcarbonate of potash is 

 added, whereby the nitric acid is taken up, and the urea set at 

 liberty. This new liquor is evaporated at a gentle heat, nearly 

 to dryness ; the residue is treated with pure alcohol, which only 

 dissolves the urea, the solution is concentrated, and the urea 



