OP ARTS AND SCIENCES. 123 



0.3132 grm. of the substance gave 0.0925 grm. of silicic dioxide and 

 0.2039 grm. of sodic fluoride. 



Found. 



10.81 

 29.45 



Dipyridine silicotetrafluoride is a pure white amorphous powder, 

 which decomposes upon standing, giving off pyridine and forming 

 tripyridine disilicotetrafluoride. 



Tripyridine disilicotetrafluoride, (C 5 H.N) 3 (SiF 4 ) 2 . — This com- 

 pound is formed by subliming the previous substance. Pyridine is 

 given off and tripyridine disilicotetrafluoride sublimes, forming a crust 

 possessing a distinct crystalline structure. It is extremely deliques- 

 cent and was not obtained in a pure state for analysis. The following 

 results of the analysis of the slightly deliquesced substance leave no 

 doubt as to its true constitution. 



0.1743 grm. of the substance gave 0.0443 grm. of silicic dioxide and 

 0.1218 grm. of sodic fluoride. 



d for 



Found. 



11.86 

 32.16 



When fluoride of silicon was passed into the ethereal solutions of 

 cinchonine or quinine, a gummy substance separated, which probably 

 possessed a constitution similar to that of the above substances. 



The constitution of these substances has been discussed at length 

 in a previous paper* by C. Loring Jackson and one of us. It remains 

 only to add, that the compounds of which dianiline silicotetrafluoride 

 is the type seem to be formed first. These are very unstable, giving 

 up one molecule of the base with the greatest ease to form compounds 

 corresponding to trianiline disilicotetrafluoride. This extra molecule 

 of the base in most cases is separated by merely washing with a sol- 

 vent as benzol, as in the case of aniline, toluidine, diphenylamine, 

 chinoline, etc. In others, as dimethylamine and pyridine, the extra 

 molecule is only given off upon standing, or by the action of heat. 



Boron trifluoride gave products with organic bases which apparently 

 possess an analogous constitution, but the substances formed were not 

 further investigated. 



*»" 



* Ante, p. 



