ON THE HORNS OF OXEN. 529 
lime, was not treated with a lead salt. The excess of lime 
having* been precipitated by sulphuric acid, the slightly acid 
liquid was evaporated, the crystals of tyrosin, which first pre- 
sented themselves in a globular form, removed, and the mother 
liquor further evaporated. The crystals which now appeared 
consisted almost entirely of leucin, but were not white. They 
were dissolved in water, mixed with hydrated oxide of lead, the 
excess of lead in the filtered liquid removed by sulphuretted 
hydrogen, and the liquid evaporated. The leucin was now free 
from tyrosin, and could be obtained perfectly white by recrys- 
tallization from water, application of animal charcoal, and re- 
peated recrystallization. It consisted of pearly laminae, which 
were readily deposited in a concentric manner, were volatilized 
when slightly heated in a glass tube, and floated about in the 
air as flocculi, like oxide of zinc. By these properties, as also 
by its great solubility in water, acids, and alkalies, the leucin 
can easily be recognised. 
Albumen, fibrin, and casein yield by a similar treatment 
much leucin, but less tyrosin : in horn the proportion is reversed. 
The quantity of both substances, however, increases to a certain 
point by this treatment of horn, in proportion to the time it is 
boiled with sulphuric acid, perhaps also by the longer action of 
the milk of lime upon the sulphuric solution of horn ; for, if horn 
be boiled only for one day with sulphuric acid, and the milk of 
lime be allowed to operate only as long as ammonia could be 
discovered by the smell, small quantities only were obtained. 
At 107° cent, the mixture of sulphuric acid and water first 
begins to boil. The boiling proceeds very steadily, when a few 
pieces of charcoal are put into the boiling liquid, and when, 
after the horn has been boiling for one day with sulphuric acid, 
the supernatant liquid be poured off from the sand and gypsum 
(which are deposited during the night at the bottom of the re- 
tort) into another vessel. After three days’ boiling, the liquid is 
light brown ; if then excess of fresh prepared milk of lime be 
added, a large quantity of ammonia is developed, the presence 
of which can, even after two days’ additional boiling, be shewn 
by a glass rod moistened with muriatic acid 
Hydrate of potash and horn . — Horn chips were melted in a 
large iron pot, with an equal weight of hydrate of potash, until, 
besides ammonia, hydrogen was also developed, and the fused 
mass, at first brown, had become somewhat paler. This was 
dissolved in boiling water, acetic acid added till a slight acid 
reaction took place, and the liquid filtered and evaporated so as 
to yield crystals. After twelve hours a rather large quantity of 
crystals of tyrosin and some of leucin had formed, which were 
separated as stated above. 
VOL. XXIV. 4 c 
