POPULAR MISCELLANY. 



571 



having this property, they are found to be 

 composed of the carapaces of tubular dia- 

 toms, formed of rings placed one upon the 

 other. Each grain of the sand is, in fact, 

 a minute tube of exceedingly fine silica, 

 forming a mineral fiber which, by virtue of 

 capillarity, retains coloring - matters with 

 the same force as do vegetable or animal 

 fibers dved under the same conditions, and 

 that without any chemical combination hav- 

 ing taken place, M. Engel has exhibited to 

 the Industrial Society of Mulhouse speci- 

 mens of silica colored with alizarine rose, 

 with indigo blue, and with a deep green pro- 

 duced by dyeing in logwood silica colored 

 with iron, in all of which cases the siliceous 

 sand had been treated as if it were cotton. 

 Other specimens showed that the same sand 

 behaved like wool in the presence of certain 

 coloring-matters, especially of those derived 

 from aniline. The experiments then make 

 known a mineral substance which has prop- 

 erties of physical structure analogous to 

 those of animal and vegetable fibers that 

 are susceptible of being dyed, the likeness 

 being given by the minute central canal, 

 which enibles each of the microscopic tubes 

 to absorb the coloring-matter through cap- 

 illary attraction, and to fix it so that it will 

 resist chemical atrents in the same manner as 

 do organic fibers similarly colored. " These 

 examples," says M. Engel, " tend to prove 

 the new fact which I have been trying to 

 establish, that the physical structure of 

 substances submitted to the process of dye- 

 ing is of much more importance than their 

 chemical composition, even if it is not the 

 only factor in the process, as my experi- 

 ments make it seem probable that it is." 



M. Soleillet on the Sahara. M. Soleil- 

 let lately made a communication to a society 

 of civil engineers on his recent journey in 

 the Sahara. This journey, the fourth which 

 he has made since 1872, was undertaken 

 chiefly for the purpose of finding what prod- 

 ucts of the soil could be made to contribute 

 to the traffic of the proposed trans-Saharan 

 railroad. He discovered coal in the Djebel 

 Aroun, saltpeter in the region of Ain-Sala ; 

 in his journey to the Soodan, he found the 

 butter-tree, which has been known since the 

 days of Park, and sent specimens of the 

 vegetable butter to M. Thenard. This prod- 



uct furnishes a stearine which melts at a 

 high temperature, and can be made to give 

 a clear white light, and has already been 

 employed by the English in tempering cer- 

 tain steels, and in oiling steam-engines. In 

 his last journey, he discovered a plant, the 

 Fernan^ a kind of Fucus^ the white juice of 

 which takes the place of pitch with the 

 Moors ; incorporated into the wood with a 

 hot iron, it makes an excellent calking for 

 boats. Hoping to find in it a substitute for 

 India-rubber, he gave some of the juice to 

 M. Thenard, who extracted from it a sub- 

 stance having properties similar to those of 

 India-rubber, except that it was not elastic. 

 It could be perfectly vulcanized, and in that 

 state was much like gutta-percha. An oil 

 was extracted from it, and a resin which 

 could be converted by heat into a beautiful 

 and brilliant lacquer. M. Soleillet was pre- 

 vented by robbers from reaching Timbuctoo, 

 but beyond Ain-Sala he discovered a large 

 extent of country marked by dunes running 

 north and south, which were crossed by 

 others running from east to west. Between 

 these dunes were ponds of both fresh and 

 salt water, which left, when they were dried 

 up, rich, natural meadows. The country, 

 having an area equal to about a quarter of 

 that of France, possesses a healthy climate, 

 and is inhabited by ten thousand people. 

 Farther on is the mountainous district of 

 Adrar, inhabited by an agricultural and 

 commercial Berber population, with whom 

 the Portuguese carried on an important com- 

 merce in the fifteenth century. 



The numan Fossil of Schlpka Cave. 



A human jawbone, found in the Schipka 

 Cave of Moravia, along with bones of the 

 mammoth and a number of rude stone im- 

 plements, exhibits, according to a descrip- 

 tion given by Professor Schaffhausen, of 

 Bonn, some remarkable and suggestive pe- 

 culiarities. It is a fragment, consisting 

 of a fore part of the lower jaw, contain- 

 ing the cutting -teeth, the eye-tooth, and 

 the two premolars of the right side. The 

 last three teeth are still undeveloped in 

 the jaw, but have been brought into sight 

 by the breaking away of a part of the bone. 

 The remarkable feature of the bone is its 

 size. The development of the teeth is that 

 of a child in its eighth year, while it is cut- 



