68 Proceedings of. Philosophical Societies. [Jan. 



raon salt. An angle of one of them scratched not only a plate 

 of steel, and ground-glass, but even plates of polished. agate and 

 rock-crystal. They were not affected by the nitric, muriatic, 

 nitro-muriatic, or sulphuric acids ; and were absolutely infusible 

 before the blowpipe, by which their surfaces were slightly oxi- 

 dated only, their brightness being restored by borax ; that salt, 

 however, did not act in any degree upon the metal, either alone, 

 or with the addition of carbonate of soda. By nitre, they are oxi- 

 dated, and they become purple or blue according to the degree 

 of oxidation, or to the depth to which it penetrates. In this 

 process, heat is evolved, but no proper detonation takes place. 

 By nitre and borax in conjunction, they may be completely dis- 

 solved before the blowpipe, the former oxidating the metal, and 

 the latter dissolving the oxide ; but as these salts do not fuse 

 together, the process is expedited by the addition of carbonate 

 of soda. The oxide thus obtained is soluble in muriatic acid, 

 from which it is precipitated white by alkalies and their car- 

 bonates ; the solution yields by evaporation a soluble muriate. 

 When this is dissolved, it yields with tincture of galls the well- 

 known gallate of titanium, exactly like that precipitated from a 

 solution of the oxide prepared from anatase. Triple prussiate 

 of potash produces a precipitate so nearly resembling the 

 gallate in colour, that in a number of trials, no constant differ- 

 ence between them could be detected. The crystals are 

 titanium absolutely pure : though found in the vicinity of 

 metallic iron, they contain none of that metal, nor do they 

 contain silica, for which the oxide of titanium has a strong 

 affinity. It was impossible to ascertain the specific gravity of 

 crystals not more than l-40th of an inch square ; but Dr. Wol- 

 laston endeavoured to ascertain whether or not they would float 

 in melted tin, and attempted to tin their surfaces for that pur- 

 pose ; but they refused to unite with that metal, nor would they 

 combine with iron, silver, or copper. Their lustre nearly proves 

 their metallic nature ; but this is completely demonstrated by 

 their perfectly conducting very feeble electricity. If a small 

 slip of zinc, in contact with one of copper, be immersed in dilute 

 sulphuric acid, bubbles of gas will rise from both metals ; but 

 if a nonconducting slip of paper be interposed, the bubbles 

 cease to be given off by the copper. Now a small hole being- 

 made in the paper, and a cube of the titanium inserted, the 

 communication was made perfect, and bubbles of gas were given 

 off from both metals. This interesting paper was concluded by 

 the remark, that the infusibility of these cubes of titanium 

 evinced, that they were not formed from a state of metallic 

 fusion, but by successive increments from the reduction of the 

 oxide in the slag ; in which manner we must likewise explain 

 the formation in nature of many metallic crystals. 



Qn t-he Difference of Structure between the Human Menv 



