Scientific Intelligence — Jrts. 187 



sons are employed in working it up. To make up the weight of 180 

 tons consumed in that place, there must be about 45,000 tu&ks, 

 whose average weight is nine pounds each, though some weigh from 

 60 to 100 pounds. According to this, the number of' elephants 

 killed every year is 22,600 ; but allowing that some tusks are cast, 

 and some animals die, it may be fairly estimated that 18,000 are 

 killed every year merely for their ivory, which is contrary to the 

 usual belief that the ivory used comes from the tusks cast by living 

 elephants. These estimates, it will be seen, are for Sheffield merely. 



26. Flexible Ivory. — M. Charriere, a manufacturer of surgical 

 instruments in Paris, has for some time been in the habit of render- 

 ing flexible the ivory which he uses in making tubes, probes, and 

 other instruments. He avails himself of a fact which has long been 

 known, that when bones are subjected to the action of hydrochloric 

 acid, the phosphate of lime, which forms one of their component 

 parts, is extracted, and thus bones retain their original form and 

 acquire great flexibility. M. Charriere, after giving to the pieces 

 of ivory the required form and polish, steeps them in acid alone, or 

 in acid partially diluted with water, and they thus become supple, 

 flexible, elastic, and of a slightly yellowish colour. In the course of 

 drying, the ivory becomes hard and inflexible again, but its flexi- 

 bility can be at once restored by wetting it either by surrounding it 

 with a piece of wet linen, or by placing sponge in the cavities of the 

 pieces. Some pieces of ivory have been kept in a flexible state in 

 the acidulated water for a week, and they were neither changed, nor 

 injured, nor too much softened, nor had they acquired any taste or 

 disagreeable smell. 



26. Air-Whistle. — Mr C. Daboll,of New London, Connecticut, has 

 invented a whistle that speaks with a most " miraculous organ " 

 whenever its services are required for the purpose of alarm or warn- 

 ing. It is designed for the use of vessels at sea or on the coast, as 

 on our eastern shores, where dense fogs prevail, and vessels are 

 liable to come in collision before they are conscious of each other's 

 approach. Its great advantage is its power of communicating sounds 

 for a distance of from 4 to 5 miles, far exceeding the largest bells. 

 An experimental one has been placed on Bartlett's Reef, and the 

 pilot of the " Lawrence " states that he has heard it when about 4 

 miles off from Bartlett's Reef, against the wind, which was blowing 

 quite fresh at the time. This was on a clear day, and when the 

 whistle was blown at his request, and also by advice of the inventor, 

 so that the distance might be marked. It is probable that, under 

 the same circumstances, the tones of a bell could not have been heard 

 more than from one half to three-fourths of a mile. The pilot of the 

 steamer *' Knickerbocker" reports, that he made the whistle during 

 a dense fog, thirteen minutes' running-time of the steamer, before 

 coming up with the station where it is located. He therefore must 

 have been some four or five miles distant from it when he heard it. 



