256 Scientific Intelligence. 
9. On the ea of Urea—Presence of Urea in the Vitreous 
Humor of the E y M. E. Mitton, (Comptes Rendus, Jan., 1848.) 
—WNitrite of canned "hhesolved in nitric acid gives off no nitrous va- 
pors, but yet readily transforms urea into nitrogen and carbonic acid. 
he carbonic acid is collected and weighed in the usual manner in pot- 
ash tubes; its weight multiplied by 1:371, gives the quantity of urea. 
This method is easy of execution, consumes but little time, and is 
reliable to the ‘001 of the weight of the urine. Substances usually 
present in this liquid are said not to affect the accuracy of the process. 
ity of urine and the quantity of urea present. The second and third 
figures after the decimal place in a specific gravity, cn nearly rep- 
resent the quantity of urea in 1000 parts of urine. ‘This empirical law 
holds good only for the secretion fen m man in a state of bani From 
animals and — men laboring under various diseases no such corres- 
pondence is fou 
illon ie also shown that the ao left on evaporating the 
liquid of the vitreous humor of the eye of the ox, man, or dog, con- 
tains 20 to 35 per cent. of urea—the ee oe being chlorid of sodi- 
um without any albumen, as stated by Berzelius. 
The aqueous humor also contains urea and chlorid of sodium. 
G. C, ScHAEFFER. 
10. On the Employment of Gun-cotton in Mining ; by M. ComBEs, 
(Comptes Rendus, Jan., 1848.)—It is known that this substance does 
not contain oxygen enough for the complete combustion of all its car- 
bon . Combes proved the presence of a large quantity of carbonic 
oxyd, after a blast _ gun-cotton, and even exploded the mixture form- 
ed with atmospheric a 
To avoid this diffieulty, chlorate of potassa was added in quantity 
sufficient to complete the combustion—80 parts to 100 pyroxyline. 
The salt finely powdered was mixed with the cotton by hand. In this 
case the effect was excellent—no combustible vapors, no odor of any 
kind could be noticed ; eg 5 parts of ppt and 4 of chlo- 
rate were equal in effec t to 30 parts of mining powde 
Mixtures with 80 parts nitrate potassa, or 70 fans of soda, were 
equally free from fumes and almost as powerful as that with chlorate. 
In the plaster rock in which the trials were made, M. Combes asserts 
that these mixtures are nearly as effective as their own weight of gun- 
— three — their weight of gunpowder, or four times that of 
asting pow 
The a of gas is the same with or without the mixture ; the in- 
creased effect must be due to the greater heat produced by the carbonic 
oxyd burning to oe aci 5. 
1] a new Process for prepari ne ar: by MM. Hov- 
are to . pei to poet 100° Fahr. Then stir in 11 pounds of quic 
the head is to be put on, and the water of the bath caused to boil as 
quickly as possible. 
