PRODUCE AND PROFITS OF THE SILK-WORM. 109 



the first ten days, by the perspiration of the chrysalides. 

 The proportion between the weight of silk which can 

 be reeled, and that of the coarse floss which can only 

 be spun, is found to be in the average proportion of 19 

 to 1 in perfect cocoons. But this does not include the 

 outer floss, of a loose furzy texture, which can never be 

 reeled. 



1000 ounces of perfect cocoons have been found to 

 produce 150^ ounces of pure cocoon. Thus every per- 

 fect ball, as soon as completed, contains more than one- 

 seventh part of pure cocoon; but this includes the floss 

 and the pellicles. I have stated the length of the fila- 

 ment at from 400 to 1200 feet, and others have esti- 

 mated the length of thread equal to from 750 to 1160 

 feet. Count Dandolo states that the filament seldom 

 exceeds 1875 feet. I have put down as the average 

 length 900 feet. Mr. Pullen has stated the same. 



Count Dandolo, by good management, usually pro- 

 duced at his establishment, 140 pounds of fine picked co- 

 coons from each ounce of eggs, in addition to the coarse 

 outside floss. But it has been found possible to pro- 

 duce 165 pounds of cocoons to each ounce of eggs, and by 

 a late account, 170 pounds have been produced in 1835, 

 by Henri Bourdon, proprietor at Ris, near Paris, and in 

 the north of France. 



It is estimated, from all the data that Europe has 

 furnished, that 2,800 worms are required, on the ave- 

 rage, to produce a pound of reeled silk. In 1790, the 

 gold medal of the society for the encouragement of arts, 

 in England, was awarded to Mr. Salvator Bertezen, for 

 having raised five pounds of reeled silk from 12,000 silk- 

 worms, which is 2, 400 silk-worms to the pound of reeled 

 silk. This average varies not very materially from the 

 results produced byCount Dandolo. The cocoons in all 

 the cases above stated must have been fine ; and superior 

 to those 8,000 cocoons from which Mr. Cobb obtained 

 three pounds of silk, including the floss as is stated by 

 him. Mr. Cobb is satisfied, that 2,400 cocoons to the 



