SILK-WORMS. 
273 
To prove, for instance, that the disorder of the 
harpions, or Riccioni, proceeds really from de- 
rangement in the functions of the skin, curable in 
some instances, it is sufficient to put several se- 
parately, in little unsized paper boxes, that are 
a certain degree larger than the worm ; and if 
those boxes are put into a place, the temperature 
of which is six or eight degrees higher than 
that prescribed for the particular age, many of 
these worms will spin a good cocoon, and will 
and untouched, without there appearing less of it than in 
the healthy worm. Having subsequently washed the silk- 
worms in water, there was deposited a powdery substance 
similar to that which the moth discharges, on first issuing 
from the cocoon. 
The knowledge of the internal state of the silk-worm in 
such circumstances, and the analysis of the saline substance 
enveloping it in the mummy state, termed calcination, were 
to lead me to important discoveries. 
I have collected with care, from the cloths on which the 
moths were placed, a quantity of this earthy substance which 
they had discharged, mixed with a liquid substance. It is of 
a reddish tint, looks very much like mould, and has no pecu- 
liar flavour, although it cannot be said to be entirely tasteless. 
It has a smell very similar to that of the cocoon. I con- 
sulted Professor Erugnatelli upon its nature, and the ana- 
lysis he gave of it presented a most unexpected result. It 
is a compound of much uric acid. This acid is combined 
with ammonia. Also phosphoric acid combined with lime 
and magnesia, forming what chemists call phosphate of lime 
and magnesia: it contains beside, carbonate of lime, and a 
small portion of animal substance. 
The extraordinary part of this analysis, is the uric acid, 
which had been imagined only to exist in the human urea, 
N 5 
