Processes in the Useful Arts. 349 



ing 14 strokes per minute, 6£ feet stroke, and lifting a column of water 

 36 feet high, and 40 inches diameter, consuming not more than 100 lbs. 

 of coals per hour. We also certify, that Mr Perkins's flexible steel piston is 

 quite tight, although at times working at a pressure of fifty atmospheres." " 



11. On the method of preparing Catechu in Bundelkund in India. 

 At the season when the sap flows most copiously, a few Gdnds take up their 



temporary residence in some solitary glen where the Khair treef (Kha- 

 dira) abounds. All the implements they require are a hatchet, a few 

 earthen-pots, and the convenience of water. The tree, after being felled, 

 is barked and chipped, whilst the sap is flowing ; and, in the meantime, 

 the earthen-pots, half filled with water, are ranged in rows over fires; the 

 chips, as soon as cut, are thrown into the water, and boiled until the in- 

 spissated juice acquires a proper consistency. The liquor is then strained, 

 and suffered to cool, and it soon coagulates into a mass, which is the 

 Catechu, the quality of which depends very much upon the freshness of 

 the tree from which it is obtained. — Captain Franklin's Memoir of Bun- 

 delkund, in the Trans. Royal Asiatic Society, vol. i. p. 276. 



12. On a new method of manufacturing Glass. By M. Legnay. 

 Take 100 parts of dried sulphate of soda, 656 parts of silica, 9340 of lime 



which has been exposed to the air, and mix them well. When the furnace 

 and pots are heated to a full red, this mixture must be put into the pot in 

 small balls. The mouth of the pot being stopped up, it is then put into 

 the furnace, and as soon as the materials have sunk, more of the same mix- 

 ture must be put in, till the pot is filled with a melted vitreous substance, 

 and a strong fire must be kept up to have the mass completely fused, and 

 as soon as possible. When the fumes diminish, small portions must be 

 taken out, to see if the glass is sufficiently refined, which generally happens 

 in about 22 hours. The glass is then fit for use, and may without risk 

 continue double the time in the furnace. 

 The following other proportions have also been given : 



1. Well dried Muriate of Soda, - - 100 parts. 

 SiUca, - - - - 123 

 Lime, .... 92 



This will be sufficiently refined in 16 hours. 



2. Dried Muriate of Soda, - - 100 

 Slacked Lime, - - • 100 

 Sand, ..... 140 

 Chippings of Glass of the same quality, - 50 — 200 



3. Dried Sulphate of Soda, - - 100 

 Slacked lime, - - - 12 

 1'owdered Charcoal, - - 19 

 Sand, ... . 225 

 Broken Glass, - - - 50—206 



• A report on Mr Perkins's engine was made to the Institute of France on the 

 31st July last, by M. Gerard, 

 f The Mimosa Catechu, which grows in great abundance in llundclkund. 



