SILK-WORMS. 
335 
cocoons, that is to say, double as much. Conse- 
quently, if the common cocoon costs, for instance, 
three francs a pound, those that are calcined and 
unstained should cost six francs a pound. 
There should be about 1100 of the calcined 
worms to form a pound and a half*. 
Stained Cocoons containing the Calcined 
Chrysalis. 
One thousand ounces of these cocoons contain 
a weight of mummy chrysali, with saline 
substance, amounting to .... 600 ounces. 
Pure cocoon 400 
Total 1,000 
The proportion of the full cocoon, and empty, 
must then be three to two. 
* I found the weight of the empty cocoon of the healthy 
chrysalis, nearly of the same weight as that from which I had 
extracted the calcined mummy. 
The spinner, however, often finds an impediment which 
prevents his drawing from the calcined quality of the cocoon, 
the same quantity of silk ; this impediment is caused by the 
lightness of the cocoon, that has the calcined worm. It is 
almost indispensable, when spinning the cocoon, that there 
should hang a weight, such as the healthy chrysalis to the 
end of the thread, to keep it steadily down in the water. If 
the chrysalis is calcined, it weighs less than the healthy one, 
and the spinner will find it a great disadvantage ; it will not 
keep in the water, nor spin steadily, and the spinner gets 
rid of it as soon as possible. 
This will show the benefit of healthy chrysalides in all the 
cocoons, as they weigh six or seven times more than the 
empty cocoon. 
