528 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



SUBSTITUTION OF CHARCOAL FOR LIME IN REMOVING HAIR 



FROM HIDES. 



The discovery of Anderson, of Scotland, that pulverized 

 charcoal effects the removal of hair from hides, has been sub- 

 jected to thorough trial by different manufacturers of leather, 

 and with very favorable results, according to reports made 

 through different journals. . Since the charcoal, however, 

 does not cause the hides to swell, a short previous liming, of 

 two or three days, is still necessary ; but this is not objec- 

 tionable, as the charcoaling prevents any injurious result in 

 addition to the action on the hair. The process can be car- 

 ried on in the ordinary lime-pits at a temperature prevailing 

 for the greater part of the year namely, 50 to 70; four to 

 five days being sufficient at a temperature of 60 to 70, 

 while seven to eight days are necessary at 40 to 50. The 

 temperature is easily regulated by steam. Among the ad- 

 vantages, the following seem to be generally conceded : A 

 decided economy of time, as well as of labor, since the sub- 

 sequent operations are rendered easier and the tanning proper 

 more rapid. The bran or dung bath may be entirely dis- 

 pensed with. The liquids act uniformly without leaving 

 specks. On account of the absence of disagreeable odors, the 

 new process is more pleasant and less injurious to health. 

 The leather is softer and better in quality, is easily worked, 

 and does not tear out in sewing. There is a gain of one half 

 to one pound in weight of leather per hide, while the char- 

 coal, considering the amount required, etc., is found to be 

 practically as cheap as lime. 14 C, 1873, CCX., 397. 



NEW PROCESS OF ENGRAVING ON COPPER. 



A new process of engraving on copper, with special refer- 

 ence to map-work, announced by Bouguet de Lagrye, com- 

 mends itself on account of its simplicity and economy of 

 cost. This consists essentially in first electro-plating, or 

 otherwise coating, the object with a thin layer of silver, 

 which is then evenly coated with a colored varnish. The 

 outline topography and lettering are next to be marked in 

 with a dry point, as is done with a diamond in engraving 

 upon stone. These lines are then to be etched by means of 

 the perchloride of iron. The labor of transferring the draw- 



