22 UTILIZATION OP MINUTE LIFE. 



at the rate of six inches per minute. The length of 

 silk furnished by one cocoon averages 1526 English 

 feet. 



The total quantity of silk spun in one year in 

 Lyons alone amounts to 6,000,000,000,000 of English 

 feet. We cannot be surprised, then, that in the South 

 of Europe the prospect of a deficient crop of silk 

 causes as great a panic as a scanty harvest of grain 

 with us. The average crop is about 80 Ibs. weight 

 of cocoons produced from the larvae hatched from 

 one ounce of eggs. But this harvest is in some cases 

 far greater, and has been known to attain 1 30 Ibs. 



In four days the silkworm has completed its 

 cocoon, in which it remains from ten to twenty days 

 in the -chrysalis state, from which, in nature, it 

 emerges as a moth. If left to itself the newly formed 

 insect makes its way out of the cocoon by means of 

 a brown liquid it secretes, and which has a corrosive 

 action upon the silk. 



To prevent this the chrysalids are destroyed either 

 by placing the cocoons for an hour upon a hot -stone, 

 by exposing them for three successive days to the 

 direct rays of the sun, or by heating them by means 

 of vapour in a copper apparatus to 60' or 75' (Cent.). 

 We are told that the Chinese used formerly to 

 produce the same effect by placing the cocoons in 

 large earthen jars covered with salt, from which they 

 excluded the air. 



