STIFLING THE COCOON OR CHRYSALIDE. 85 



France, ovens are used for destroying the insect. The 

 cocoons are placed in oblong shallow baskets covered 

 with a paper, and over this a cloth, and these are placed 

 in an oven, the heat of which should be very nearly that 

 of the oven after the bread is drawn. Thus wrapped 

 up and exposed during half an hour or an honr, the 

 chrysalides taken from the centre of the basket will be 

 found dead. On removal from the basket, they are cov- 

 ered closely will blankets for a few hours, and then dried 

 in the sun. Steam of boiling water is a mode of de- 

 stroying equally effectual. Boiling water is poured into 

 a large wooden trough or vessel to the depth of two feet. 

 Over this the cocoons are placed in a basket of the same 

 form and size : this is covered close with wollen cloths, 

 and the basket is lowered to within an inch of the sur- 

 face, that the steam may pervade the whole mass new 

 quantities of boiling water being added to keep up the 

 steam, in two hours the chrysalides will be found dead. 

 The cocoons are then removed and covered close with 

 woollen cloths, and afterwards spread in the sun to dry. 

 189 to 200 is the heat usually prescribed for killing 

 the chrysalides, either in the oven or by steam. 



Stifling by steam, observes M. Amans Carrier, injures 

 the lustre, particularly of the white silk. And Mon- 

 sieur Baume, the celebrated chemist, has also remarked, 

 that in the modes usually adopted for the destruction 

 of the chrysalides, the cocoons were rendered harder, 

 and more difficult to reel than where no artificial heat 

 had been applied ; and that the lustre is also injured in 

 the process of baking. His mode consisted in placing 

 the cocoons in large boxes, in layers six inches deep : 

 on these spirits of wine were sprinkled from a watering 

 pot, and equally distributed over the whole cocoons, in 

 the proportion of half a pint to every superficial foot of 

 surface. On these another layer six inches deep was 

 placed, and a like proportion of spirits of wine distri- 

 buted over the whole ; and so continuing till the box 

 was filled. All being covered during 24 hours, a spon- 



