OF ARTS AND SCIENCES. 21 



the uvea fluosilicate only amnionic fluosilicate, silicic acid, and cyanuric 

 acid ; but from the aniline fluosilicate a new substance, which gave a 

 precipitate of gelatiuous silicic acid with water, and contained more 

 silicon and fluorine than the fluosilicate. He did not, however, identify 

 it with the substance made by Laurent and Delbos. We may add, 

 that some years later W. Knop and W. Wolf * describe the aniline 

 fluosilicate more iu detail. 



The results of our work on this subject may be summarized briefly 

 as follows. Aniline forms with fluoride of silicon a compound having 

 the formula (C 6 H 5 NH.,) 3 (SiF 4 ) 2 , which sublimes without alteration, 

 but is decomposed with water forming aniline fluosilicate and silicic 

 acid ; when heated with an excess of aniline it is converted into another 

 compound having the formula (C G H.NH 2 ) 4 (SiF 4 ) 2 , and the same sub- 

 stance is formed when fluoride of silicon acts on aniline at high tem- 

 peratures. This second product is unstable, breaking up spontaneously 

 into the first and free aniline. The following bases also give com- 

 pounds containing three molecules of the base to two of fluoride of 

 silicon : paratoluidine, orthotoluidine, parachloraniline, diphenylamine, 

 dimethylaniline, chinoline, and dimethylamine, the last giving also a 

 compound having the formula ((CH 5 ) 2 NH) 4 (SiF 4 ) 2 . On the other 

 hand, we have not succeeded in obtaining from ammonia a compound 

 of the formula (NH 3 ) 3 (SiF 4 ) 2 . 



We propose to call these substances silicotetrafluorides, a clumsy 

 name, it is true, but one which will designate them with certainty, 

 whereas all the simpler names, such as silicofluoride or fluosilicide, 

 have been used for the fluosilicates at one time or another, and might 

 therefore lead to confusion. 



The remainder of the paper contains the detailed account of our 

 experimental results, and at the end a discussion of our views in regard 

 to the constitution of the silicotetrafluorides. 



Products of the Action of Fluoride of Silicon on 



Aniline. 



Trianiline Disilicoletrafluoride, (C 6 H 5 NH 2 ) 3 (SiF 4 ) 2 . — This sub- 

 stance was prepared by passing fluoride of silicon over aniline. The 

 fluoride of silicon was made in the usual way, from calcic fluoride, 

 sand, and sulphuric acid ; but as we found that a glass flask after 

 using it two or three times became perforated by the small quantities 

 of hydrofluoric acid formed in the process, we replaced it by a thick 



* Chem. Centralblatt, 1862, p. 401. 



