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If the hot air of a stove is employed, the cocoons may be placed in the 

 oven with the doors open, but great care must be used to see that the 

 silk does not become scorched. If steam is employed, the cocoons 

 may be placed in a colander over a vessel of boiling water. Do not allow 

 the water to boil too hard, as only the steam must reach the cocoons. 



A method of choking cocoons adopted by Mr. T. A. Keleher, of 

 this Departraent, and now largely followed, consists of placing the 

 cocoons in an air-tight box of about 24 cubic feet capacity and with 

 them a saucer containing about half an ounce of liisulphid of carbon 

 and leaving over night. It is best to open one or two of the cocoons 

 to find if the chrysalides are dead; if not, the operation must be 

 repeated. Care should be exercised that no fire of an}^ kind be brought 

 into the vicinity during this operation, as the bisulphid of carbon is 

 very inflammable. 



Cocoons to be dried should never be placed in layers of more than 

 4 inches depth. The shelf or tray that contains them should be per- 

 forated in order to allow air to circulate. They may be placed in the 

 sun daily and dried in much the same manner that fruit is dried on a 

 farm, carrying within doors at night or when rain threatens. At the 

 Department a large fruit evaporator is being used with great success 

 to dry cocoons quickl3^ Only a slow fire is m?Kntained, and the heat 

 is never allowed to rise very high. When a cocoon is thoroughly dried, 

 the chrysalis can be crumbled between the fingers into a powder. 



The thread of a cocoon is continuous with that of the web and 

 diminishes in diameter within. Its length varies from 1,200 yards to 

 1,600 yards. Different races, sexes, and conditions of rearing often 

 produce notable differences in weight of cocoons. Thas the weight 

 may vary from 155 to 320 cocoons to the pound (340 to 700 to the kilo- 

 gram) for "green" or newly spun cocoons or 465 to 960 for dried 

 ones. A thoroughly dried cocoon weighs hut one-third as much as a 

 newly spun one; or, in other words., the choking and drying of a cocoon 

 causes it to loose 66 per ceyit of its original weight. 



In the United States, as the market price of cocoons at present is 

 based on the rate of so much per dried pound, the producer should 

 ahvays ship them in this condition, as by so doing he saves practically 

 two-thirds of the cost of transportation, does away with the danger of 

 staining otherwise perfect cocoons, thereby lowering the grade of all, 

 and at the same time gives a standard basis of weight, which must 

 otherwise be assumed (if cocoons are unchoked) to be "green" from 

 the time they reach the consignee. It will readily be seen that if 

 cocoons are about 16 days old or thereabouts when received, the shrink- 

 age has already been in operation for some time and the basis assumed 

 is not a true one. 



Often two or more worms are inclosed in the same cocoon. Cocoons 

 formed from such collaboration are larger than single ones, irregular 



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