52S ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



An experiment was lately made with this signal-light, in 

 which the lamp was thrown overboard from a steamer, and 

 drawn along behind, by means of a string, at a short distance 

 from the stern. When the lamp touched the water a bril- 

 liant flame shot out immediately from the opening, and, al- 

 though it was continually dragged under water by the mo- 

 tion of the vessel, the light remained unextinguished, even 

 after the lamp was submerged. After a time the string was 

 cut, and the lamp allowed to float behind, and it was visible 

 for a long distance from the light disseminated around it. 



PREPARATION OF HIDES. 



The following method is recommended for preparing leath- 

 er. Begin by soaking the skin or hide eight or nine days in 

 water, then put it in lime ; take it out, remove the hair by 

 rubbing, and soak again in clear water until the lime is en- 

 tirely out. Put one pound of alum to three of salt, dissolve 

 in a vessel sufficiently large to hold the hide; soak the hide 

 in it three or four days; take it out, let it get half dry, and 

 then beat or rub until it becomes pliable. Leather prepared 

 by this process will not do well for shoes, but answers for 

 ham-strings, back-bands, and other purposes on the farm. 

 18 A, Nov ember 3,1871,184. 



GREASING LEATHER. 



In a recent article in a German journal it is stated that 

 the idea that leather must be perfectly dry in order to take 

 up grease or fat is entirely erroneous ; the fact being, on the 

 contrary, that wet leather can be much more readily satura- 

 ted with these substances. This, it is said, is due to the fact 

 that the pores of dry leather are almost completely closed, so 

 that the absorption is very slow, while wet leather is expand- 

 ed, flexible, and the pores wide open. When warm grease 

 or oil is applied to leather in this condition, it is taken up su- 

 perficially, and as the moisture evaporates the oily matter oc- 

 cupies the space vacated, and penetrates through the entire 

 substance. For this reason it is that when wet leather is dried 

 without any application, it often becomes brittle and unser- 

 viceable, a condition which is prevented by a previous coat- 

 ing of grease. The same writer advises very strongly to have 

 the flesh side of the leather soles of boots and shoes outside. 



