268 
THE ART OF REARING 
silk, which is the substance the least susceptible 
of being affected and corrupted ; but during this 
operation, or immediately after, heterogeneous 
substances being no longer in contact with the 
animal to support or aid it, the vitality diminishes, 
and the chemical action of these said substances is 
facilitated. 
The worm or chrysalis is then found reduced in 
a short time to a mummy state. 
There is sometimes a species of white efflo- 
rescence formed round the mummy, of saline, 
earthy, and alkaline particles, that have acted 
upon each other *. 
* From tlie moment I knew the disorder called segno, and 
that I particularly observed the calcined worm or chrysalis, I 
did not hesitate in deciding' that it must depend on chemical 
attractions aud combinations, as I before stated. This can 
hardly be mistaken on seeing the animal texture so altered, 
and converted into a hard and incorruptible substance. 
I removed with extreme ease the white and saline sub- 
stance which formed the envelope of the calcined worm. I 
analyzed it; and besides that, sent it to be analyzed by my 
friend M. Brugnatelli, Professor of Chemistry at Pavia. 
This analysis, as well as that of the earthy substance de- 
posited by the moth when it first issues from the cocoon, were, 
according to my own opinion, to reveal some very important 
facts ; and I was not mistaken. 
The species of calcination which covers the mummy of the 
silk-worm or chrysalis in the cocoon itself, is principally- 
composed of the earth termed magnesia, of phosphoric acid, 
and ammonia, or volatile alkali. 
There is no bombic acid found in this composition, which 
