MECHANICS AND USEFUL ARTS. 73 



appears to be the reason why the colored silk that was obtained in those 

 experiments was neither uniform in tint nor of a good c -lor. Others, 

 however, still persist, in a conmry opinion. M. Itoulin commenced his 

 experiments by sprinkling iiidi//o <>V.T the mulberry leaves, and obtained 

 blue cocoon* ; he then experimented with chlca, a fine red dye extracte 1 

 from the Ltiijnnnia, c/tic.a, which the Indians of Oronoco employ to dye 

 their skin, and obtained cocoons of a red c ( >lr,r with a tolerably uniform 

 tint, and of a permanent, dye. lie still continues these investigations, 

 hoping to obtain siik ready dyed of all kinds of colors. 



ARTIFICIAL CULTURE OF OYSTERS. 



The plan of M. Coste, of France, for propagating oysters, which 

 under the auspices of the French Government is now in mo.st successful 

 operation, is substantially as follows : M. Coste gets fresh oysters for 

 propagation from the open sea ; he turns to advantage those that are 

 rejected by the trade ; and, lastly, he collects the myriads of embryo 

 oysters which, at each spawning season, issue from the valves of the 

 oyster, and which are now lo^t to commerce for want of some contrivance 

 to prevent their escape and inevitable destruction. Every oyster produces 

 from one to two million of young ; out of these not more than ten or 

 twelve attach themselves to their parent's shell ; all the rest are dispersed, 

 peri-h in the mud, or are devoured by fish ! Now if bundles made of 

 the branches of trees, fagots of brushwood, or any similar objects, be 

 let down and secured to the oyster banks by weights, the young oysters 

 will, on issuing from the parent's valves, attich themselves to these 

 fagots, and may, on attaining perfect growth, be taken up with the branches 

 and transported to places where it is desirable to establish new oyster-beds. 

 A model plan for breeding oysters may be seen in the lake of Fusaro, in 

 Italy, where mussels and oysters are cultivated with much success, 

 where almost the entire quantify of spawn is developed without toss. 



One of the beds of oysters thus prepared by M. Coste, at the mouth 

 of the river Auray, in France, yielded the first year after it was matured, 

 over 20,000,000 of good merchantable oysters. 



ON SOME OF THE SOURCES AVAILABLE FOR THE SUPPLY OF 



POTASH. 



Three or four years ago MM. Maumcne and Rogelet patented in 

 England a method for obtaining potash from Suint, the name given 

 by the French to a compound of potash and some organic acids, 

 which is excreted in the sweat of sheep and found on the wool. This 

 compound is easily soluble in water, and is obtained from the wool 

 by simple washing ; the solution may then be evaporated, and the 

 potash obtained by calcination and lixiviation. Suint forms about 

 15 per cent of the weight of the raw fleece, and yields 33 per cent 

 of potash, so it is easy to see that if all the scourings of all the wool 

 produced was worked up, the supply of alkali from this source alone 

 would be very considerable. MM. Maumene and Rogelet have, in 

 fact, calculated that the washings of the raw fleeces from the 47,000- 

 000 of sheep in France would produce nitrate of potassium enough to 

 charge 1,870,000,000 cartridges, which is no doubt the most useful 

 application of the product they can conceive. 



Another small source of potash is beet-root juice. This is of no 



