703586-1871-Silkworms-Suffocation-of-Chrysalids- — Page 1

516 THE HONGKONG GOVERNMENT GAZETTE, 25TH NOVEMBER, 1871.

No. 161.

GOVERNMENT NOTIFICATION.

The following Copy of a Report by Mr. Consul COLNAGHI on a New Method of suffocating Chrysalids of Silk-worms, invented by Professor CASTROGIOVANNI, of Turin, is published for general information.

By Command,

J. GARDINER AUSTIN,

Colonial Secretary.

Colonial Secretary's Office, Hongkong, 24th November, 1871.

ITALY.

TURIN.

Report by Ir. Consul Colnaghi on a New Method of Suffocating Chrysalids of Silkworms, invented by

Professor Castrogiovanni, of Turin.

In my Report "On the Yield of Cocoons in Italy in 1869," I had occasion to mention Professor Castrogiovanni's apparatus for the destruction of the chrysalids of silkworms in the cocoon.

In the course of last year I witnessed the Pneumatic Oven (Forno Pneumatico), as it is termed by its inventor, at work. The results appeared to me of sufficient practical importance to warrant a more detailed notice than I gave at first, particularly in view of the recent introduction of the silk husbandry into certain of our Australian colonies, and the efforts of the Silk Supply Association to promote the production of silk in India.

The ravages of the silkworm disease have caused considerable attention to be given of late years to the destruction of the chrysalids of the worms. Now, when the yield is uncertain and cocoons at high rates, an accident in the baking is a matter of vital importance. In happier times plenty produced carelessness, and low prices indifference to waste.

The destruction of the chrysalids is generally effected either by suffocation under the influence of hot air, or suffocation by steam.

The advantages of the hot air system are to be found in the good and dry condition of the cocoons, Its principal defect consists in a too complete when the operation has been successfully carried out. desiccation of the gummous substance contained in the cocoons, thus preventing the easy reeling-off of the thread..

The disadvantages of the ordinary steam oven are of an opposite character. The cocoons instead of being too dry are over-moistened by the condensation of the vapour, and have a tendency to spoil and rust. The chrysalids, moreover, though killed, is 1 ot dried, and is liable to become putrid, to the detriment of the surrounding web.

In Professor Castrogiovanni's system, the novelty of which consists in the application, the cocoons are submitted to a steam bath, at an uniform temperature of 100° centigrade. The steam rising practically uncondensed,* under an iron receiver, which covers the cocoons, the chrysalids are sut- focated by the diffused heat, which penetrates thoroughly, while the web of the cocoon retains its natural condition.

The following tracing will serve to explain the nature of the apparatus:-

孩

B

* The condensation that occurs is very slight. On the cocoons being placed in the scales immediately after being steamed, when I was present, there was an increase of 3 per cent. on their weight. Twenty minutes later they were of the same weight as before undergoing the operation.