A6 Proceedings of the British Association. 
whole is then agitated with a wooden stirrer and kept heated. 
Nitrie acid is thus evolved in considerable quartity and: purity, 
from a large surface, and in such a manner that all the acid evol- 
ved must necessarily pass through the melted wax. This method 
answers the purpose very completely ; the process i$ cheap and | 
rapid, and the residuum, being merely a little solution of sulphate 
of soda, is easily removed. When it is desired to employ chlo- 
rine in place of nitric acid as the bleaching agent, the same pron 
cess may be adopted. 
Prof. Gregory read a paper on the ON: AO of urea in urie 
acid. By the action of peroxide of lead on uric acid, Liebig 
and Wohler obtained from it oxalic acid, allantoine and urea, and 
they considered the latter as existing in the uric acid, combined 
with urile. ‘The author having found that urea, unlike most or- 
ganic substances, resists the oxidizing agency of permanganate of 
potash, thought that if urea could be obtained from uric acid by 
the action of that salt, the argument for its preéxistence would 
be much strengthened ; as, if only the elements of urea were pre- 
sent, the oxidizing agency of the permanganate would most 
likely prevent its formation. On trying the experiment, a large 
quantity of urea was obtained, along with oxalic acid, and a new 
acid probably formed by the oxidation of allantoine. ‘The au- 
thor further described the acetate of urea, a salt formed in his ex- 
periments. 
Prof. Gregory then exhibited a new process, communicated by 
Prof. Liebig, for preparing the very singular and beautiful com- 
pound termed murexide by Liebig and Wohler, and purpurate of 
ammonia, by Prout. The process is quite certain, and very pro- 
ductive. It consists in adding a boiling solution of 7 grains of © 
aloxan, and 4 grains of aloxantine in 240 grains of water, to 80 
grains of a cold and strong solution of carbonate of ammonia. The 
mixture instantly acquires a deep purple color, and on cooling, 
deposits the golden green crystals of murexide. 
On the relation of form to chemical composition, by Dr. Schaf- 
haeutl. The object of this paper is to explain the circumstan- 
ces under which certain modifications of form take place in Gra- 
phite, (as also in others generally considered to be elementary,) 
and to prove their SraneriPe with changes of an entirely chemi- 
. 
cal nature. 
