158 THE LACTATES, AND UREA AS IT EXISTS IN URINE. 
should furnish 27, (or 30 for 1000,) which circumstance con- 
firms us in the idea that a large part of the lactate is volatilliz- 
ed by concentration. 
Lactate of urea, either natural or artificial, crystallizes in 
elongated, six-sided prisms, with oblique terminations. These 
crystals are white, hygrometric, very deliquescent ; their taste 
is sharp and pungent ; they are very soluble in water, in al- 
cohol of 38°, in etherized alcohol, but much less in pure ether. 
Heated moderately, they first fuse, then volatillize without de- 
composition, and then sublime. If the temperature be raised, 
a black, carbonaceous residue is left behind. 
When the lactate of urea is heated with hydrate of zinc, and 
the product treated with absolute alcohol, the urea is sepa- 
rated, and the residue, insoluble in alcohol, on being dis- 
solved in boiling water, will furnish crystals of lactate of 
zinc. 
This new mode of obtaining urea, it appears to us, should 
supersede that which consists in previously converting it into 
a nitrate. To convince us of this, we treated the same quan- 
tity of urine, 1, by nitric acid and the usual means ; 2, by 
slacked lime ; 3, by hydrate of zinc. In the three cases, the 
quantity of urea obtained was nearly the same ; nevertheless, 
by nitric acid, there are more chances of loss, through the easy 
decomposition of the nitrate by heat ; by lime, a product was 
obtained, which it was difficult to purify ; whilst, by hydrate 
of zinc, the manipulations are easy, and the lactate of zinc 
may be used to prepare lactic acid, or other lactates. 
The lactate of urea is formed, in the 100 parts, of 
Dry urea, 49.61 
Lactic acid, (as it exists in saline combination) - 50.31 
This composition represents in atoms : 
Lactic acid, supposed to be anhydrous, 1 atom. 
Urea 1 " 
Water ----- 1 " 
