330 
THE ART OF REARING 
being of a gummy nature, dissolves and is lost in 
the cauldron. 
The proportion between the quality of spun 
silk obtained from the cocoon and that of the floss 
or above-mentioned, is on an average of about 
from 1 10 to 40, or 11 to 4 ; that is to say, that 
there are four ounces of floss to eleven ounces 
of silk. 
Generali)’, in 1 50 pounds of cocoons there will 
be found about pounds of double cocoons, 
formed by two worms, and are worth not quite 
half a single cocoon. 
About 506 feet of the single thread of silk, spun 
and extracted from silk-worms of three casts, 
weighs one grain ! 
The cocoon of the small worm of three casts 
yields 2 3 o 4 grains of silk ; and if we make an 
average calculation, we shall extract about 
11 ounces of silk from 3000 cocoons, weighing 
7-J pounds. 
The same cocoon yields about 1166 feet long 
of the single thread ; in one ounce of this spun 
silk will be found a length of 291,456 feet ; 
458 feet 4 inches of spun silk, extracted from a 
common cocoon of four casts, weighs one grain. 
This common cocoon of the silk- worm of four 
casts yields 3/^% grains of silk ; because, on an 
average, there are about 1 1 ounces of spun silk 
