12 BULLETIN 824, U. S. DEPARTMENT OF AGRICULTURE. 



revolve in a corrugated cylinder at a rate of from 3,000 to 3,500 revo- 

 lutions per minute. The flower heads are fed into a hopper, either by 

 hand or automatically through a chute, and are thrown with great 

 force against the corrugations on the inside of the cylinder by the re- 

 volving discs. The discs do not rub against each other or the cylin- 

 der ; the flowers are simply cut to pieces by the force of their impact 

 against the sharp corrugations. In a mill of this kind the cylinder 

 opens into a large box or cloth bag of close weave. If a box is used, 

 it must be provided with a number of cloth "chinmeys," which may 

 be supported by a wooden framework. The idea of the cloth is to 

 hold in the fine insect powder while allowing the air, which is fanned 

 into a very strong current by the revolving discs, to filter through. 



When flowers imported from Japan are ground it is necessary first 

 to run them through a disintegrator, which consists commonly of a 

 mill built like an ordinary large, coarsely -grinding domestic coffee mill. 

 Before being shipped from Japan, insect flowers are wrapped in rattan 

 or similar material, and compressed into as small a bulk as possible in 

 a press . Ordinarily four of these little bales, each of which weighs about 

 100 pounds, are wrapped together in burlap with metal bands and 

 wooden strips for shipment. The flowers are so compressed in these!- 

 packages that the use of the disintegrator is necessary. From the 

 disintegrator the flowers travel on a belt to a chute through which they 

 fall to the floor below. An electromagnet is so arranged under the 

 belt that particles of iron, like nails, which may be present in the bale, 

 are removed as the flowers pass down the chute. On the floor below 

 the flowers may be fed directly into the hopper of the disc mill, or they 

 may be run first through a cutter, which further breaks them up and 

 expedites the final pulverization. 



In either process the powder becomes quite warm in the grinding, 

 thus losing part of its moisture, but not, apparently, any of its insecti- 

 cidal constituents. This loss in moisture, together with a slight 

 mechanical loss in the milling process, amounts to 6 or 7 per cent by 

 weight of the flowers ground. 



In grinding insect flowers it is not customary to add any material 

 to assist the pulverization. Nor, with the exception of large stones, 

 which may have been added to the bale, and certain bits of iron which 

 are taken out by an electromagnet, is anything removed from the 

 flowers as they are received. Such foreign matter as stems, either 

 adhering or loose, sand, and dirt is allowed to remain. 



In Japan the process of manufacture is as follows (292): The 

 flowers are dried in the shade for one day in the summer, after which 

 some 8 pounds are placed in a stone mortar and powdered for about 10 

 hours. This powder is then put through a sieve, and dried by steam 

 heat at from 80° to 90"^ for 4 or 5 hours in a drying room. When well 

 dried it is packed in tin containers. In the sieving process from 20 



