MECHANICS AND USEFUL ARTS. 79 



and which weighed nearly two hundred pounds. The same firm, in 1851, sent 

 to the World's Fair, London, the widest, finest, and largest piece of iyoiy 

 ever sawed out. By machinery, invented in their own factory, they sawed 

 out (and the process of sawing did the work of polishing at the same time) a 

 strip of ivory forty-one feet long and twelve inches wide. It took the pre- 

 cedence of all the specimens sent in by England, France, or Germany, and 

 received rewarding attention from the Commissioners. 



The most costly tusks, or portions of the tusks, are those which are used 

 for billiard-balls. What are termed " cut-points " of just the right size for 

 billiard-balls, from 2j! to 2 inches in diameter, brought the highest price 

 (25) per cut of any ivory offered in the London market at the late sales. 

 Billiard-ball making has of late become a very important item of manufacture 

 in this countiy. 



The teeth from the west coast, with the exception of " Gaboon," are less 

 elastic and less capable of bleaching than those that come from other por- 

 tions of Africa. The west coast tusks are much used for knife-handles. 

 Since the French have possessed Algeria, France receives a considerable 

 portion of ivory from Central Africa by the large caravans that travel from 

 Timbuctoo northward. 



Ivory is also furnished by the walrus, or sea-horse, and commands a price 

 equal to the best qualities of elephant ivory. It is, however, too hard and 

 non-clastic for many purposes, and has the disadvantage of being too small 

 to cut up profitably. 



NON-INFLAMMABLE FABRICS. 



In the long list of casualties that we are frequently called upon to read, 

 appear too often the accounts of women and children burned to death by 

 the ignition of their clothing. The frequency of these accidents is startling 

 and painful, not only here, but in those countries where the same style and 

 material in dress prevails. As these causes generally occur in consequence 

 of an immediate contact with the burning coals of a grate or stove, it seems 

 but just to conclude that the present mode of wearing extended skirts ren- 

 ders the risk much greater, and increases the danger of a fatal sacrifice to 

 fashion. Some of the garments of women are extremely inflammable, and 

 these are worn so near to the person that it becomes next to impossible, in 

 case of their ignition, to divest the wearer of them until she is seriously 

 injured. This is particularly the case with the lighter materials of which 

 party and evening dresses are composed; and this fact should impress itself 

 upon the public mind here, as it has in England, where the Queen, a short 

 time since, requested the Master of the Mint, Professor Graham, to super- 

 intend a series of experiments with a view to determine if these fabrics 

 could by easy means be rendered non-inflammable. The professor entrusted 

 the inquiry to two distinguished chemists, Dr. Oppenheim and Mr. Versmann. 



From an article on the subject, contributed by Robert Hunt to the London 

 Art Journal, we learn the prominent points of their report. They com- 

 mence by stating some of the peculiarities of cotton and linen, and then 

 enumerate the numerous articles which have been from time to time em- 

 ployed and recommended by different parties to render them flame-proof, 

 such as alum, borax, silicate and carbonate of potash, sulphate of iron, sul- 

 phate of lime, the chloride of ammonium, and other salts of ammonia; but 

 state that none of these experiments resulted satisfactorily. 



