86 ANNUAL OF SCIENTIFIC DISCOVERY. 



illuminating- power of fully eight per cent. ; the materials are inex- 

 pensive, may be repeatedly used, and give no unpleasant odor; the 

 impurities are disinfected and converted into marketable products of 

 great value ; less resistance is opposed to the passage of the gas than 

 by lime, and the quantity of gas from a given weight of coal is con- 

 siderably increased. London Mining Journal, April 27. 



NEW PROCESS FOR TANNING. 



A PATENT has been recently granted for an improved process of 

 tanning, of which the following is a description. The hides or 

 skins during the process of tanning are submitted to electric or gal- 

 vanic agency, by placing a plate of lead and a plate of zinc on oppo- 

 site sides of the pit, and connecting them by a metal strap above the 

 level of the water. The skins are suspended in the pit for a week, in 

 water, which is gradually converted into ooze, or tanning liquor, of 

 the strength of 15 saccharometer, by the addition of bark ; or the water 

 is removed and ooze substituted for it. The strength of the ooze is 

 successively increased 5 every week, until it attains 45, when the 

 tanning operation is completed. London Chemist, January. 



NEW PROCESS FOR THE PRESERVATION OF TIMBER. 



MAJOR HAGNER, in his report to the United States Ordnance Board 

 of observations made during a recent military tour in Europe, gives 

 the following account of Dr. Boucherie's process of impregnating 

 timber with a solution of sulphate of copper. He confines the ap- 

 plication, generally, to soft woods, and exhibited, among other articles, 

 a work-box and secretary made of a tree within three months after it 

 was cut, which proves the wood to be well seasoned. The color 

 given by the sulphate of copper is quite pretty and peculiar, being in 

 reddish and brown streaks and shades, not unlike the effect of paint- 

 ing. After varnishing, the appearance is rich, and is said to be per- 

 manent. Dr. B. shows a pine block sawed into three sections, but 

 not disconnected, which has been buried in a fungus pit for six years. 

 The two side sections were impregnated by means of the natural ac- 

 tion of the sap vessels, the one with bichloride of mercury (corro- 

 sive sublimate) as recommended by Kyan, 800 grammes of 1.5 per 

 cent, strength ; the other with 800 grammes of sulphate of copper, 

 of 1.5 per cent. The centre section was left in its natural state. 

 This last portion, and that impregnated with the bichloride, are 

 equally and completely rotten, the fibre destroyed, and the wood 

 crumbling into dust, while the section impregnated with the copper is 

 perfectly sound and good. Sleepers on railways impregnated with cop- 

 per have been in use six years and are still sound. The price for such 

 sleepers is from ten to twelve francs per metre cube. The process of 

 impregnation is conducted in the woods ; the logs are laid side by 

 side, the large ends cut square by a saw, and arranged on the boundary 

 lines of a square, inclining from but to branches. A trough commu- 

 nicating with the reservoir is carried all round the square, above the 



