608 AITNUAL RECORD OF SCIENCE AND INDUSTRY. 



brushing or pressure. This coating is fixed, after drying, by 

 coagulating the albumen by heated steam, the fabric being- 

 then placed in a bath of perchloride of tin. The metal pre- 

 cipitates upon the zinc in a finely divided condition, and the 

 article, after being well rinsed with water and dried, is put 

 through a glazing machine, which imparts brilliancy to the 

 tin coatino'. Beautiful results can be obtained for decorative 

 purposes by printing or tracing designs, and linen cloth thus 

 tinned could be employed in many cases as a substitute for 

 tin-foil, as an elegant, tenacious water-proof wrapping. 6 C 

 May 22,1^1^,20^. 



1 

 J 



HARDENING STEEL TOOLS, ETC. 



The following secret, unpatented composition, suggested 

 by the chemist Kulicke, has been employed with success at 

 Saarbriicken for restoring burned steel to its primitive con- 

 dition ; and as it affords a peculiarly hard metal, it is also 

 used for tempering steel tools that are too soft, or may have 

 become so by use, as chisels, saw-blades, etc. Although ratli- 

 er expensive, it is really an economical treatment where large 

 numbers of steel tools are used. Burned steel heated to a 

 cherry red, and forged somewhat on an anvil, is plunged into 

 a well-mixed, doughy mass (in a box near by) composed of 

 tartaric acid, six ounces ; cod-oil, thirty ounces ; charcoal 

 powder, two ounces ; bone black, eight ounces ; beef tallow, 

 ten ounces ; yellow prussiate of potash, five ounces, and burn- 

 ed hartshorn, three ounces, and is then completely cooled in 

 water. Steel tools are similarly treated. Small articles of 

 cast iron, such as wheel-boxes, axle-bearings, etc., may be suc- 

 cessfully case-hardened by being plunged red-hot into a mixt- 

 ure of ten buckets of urine, five pounds of whitening, and 

 four pounds of salt. 1 8 (7, June 4, 1873, 368. 



ARTIFICIAL PRODUCTION OF FLUORIDE OF CALCIUM. 



Among other mineral substances which the chemist has 

 succeeded in producing artificially in his laboratory may 

 now be mentioned fluoride of calcium, in crystallized forms, 

 identical with those of the native compound. A combina- 

 tion of fluor-spar and barytes, identical with a native one, 

 well known to mineralogists, has also been manufactured. 

 14.4, J'wZy 19, 1873, 81. 



