MECHANICS AND USEFUL ARTS. 129 



as well as the long intermediate cavern. — Journal Franklin Insti- 

 tute. 



PliotograpJiy and Gunnery. — During the late experiments at 

 Fortress Monroe, photographs were taken of the target from an 

 adjacent bomb-proof, so as to record the exact amount of damage 

 effected by each shot. 



Fuel in the Form of Powder. — Mr. Crampton's process, de- 

 scribed in a few words, consists of an arrangement by which a 

 portion of finely powdered coal is blown into a furnace, where, 

 at first, a small fire has been lighted. This immediately bursts 

 into flame, and by properly adjusting the proportions of air and 

 coal powder, a flame is then regularly kept up, giving out an intense 

 heat, and leaving little or no residue in the shape of clinkers or ash. 



Drying of Wood. — For this purpose, the wood is kept for some 

 hours under boiling water, whereby all its soluble parts are with- 

 drawn. It is next left to dry, and then boiled for some time in a 

 solution of bo^'ax, which causes the albumen to become soluble, 

 and to escape from the pores. After this proceeding, the wood is 

 placed in stoves heated by steam, and in 3 days has become sea- 

 soned. — Cosmos. 



Conservation of Wood. — M. Morin states that he has in his pos- 

 session wooden water-wheels which have been in use for more 

 than 1,500 years, for the evacuation of water from a copper mine. 

 These wheels have a diameter of 6 metres ; and, on a portion of 

 the wood being analyzed by M. Payen, it was found to be per- 

 fectly sound, and to be partly converted into a compound of cel- 

 lulose and copper, precisely similar to that which is formed in 

 Boucherie's process for the preservation of wood by sulphate of 

 copper. 



Tanned Cotton. — This" is prepared by treating cotton, fabrics in 

 a similar manner to that in which skins and hides are treated for 

 the manufacture of leather. Cotton thereby acquires greater 

 strength, and is more enabled to resist the effects of moisture 

 and disintegrating effects. — Cosmos. 



Strengthening and Rendering Woven Tissues Impermeable to Water. 

 — M. Neuman, in " Les Mondes," Sept. 16, 1869, gives this 

 method : A sulphuric acid bath is made, containing acid vary- 

 ing in strength from 40° to 66° Beaume (specific gravities 1384: 

 and 1850,) and kept at a temperature of 57°. The woven tis- 

 sues, cotton or linen, are rapidly passed through this bath, being 

 only left in contact with the acid for from 10 seconds to two 

 minutes, according to the nature of the tissue, which is immedi- 

 ately after passed through very cold water, and next submitted to 

 a thorough washing process. The effect of the action of the acid 

 is an incipient dissolution, and formation of a varnish-like matter, 

 which, especially after it has been regularly spread over the fab- 

 ric and incorporated therewith, by hot-jDressing and calendering, 

 greatly increase the strength of the fabric, rendering it also im- 

 pervious to water. 



Method of Producing upon Iron a Durable Black, Shining Var- 

 nish. — Take oil of turpentine, add to it, drop by drop, and while 

 stirring, strong sulphuric acid, until a syrupy precipitate is quite 



