838 



SIE B. C. BEODIE ON THE CALCFLrS OF CHEMICAL OPERATIONS. 



of view, but little value could be attached to any inference at which we thus arrive ; 

 for the conclusions drawn from six or seven instances, accidentally selected, would not 

 improbably be negatived by a more extended experience. But our judgment is in truth 

 based upon considerations of a far more complex character ; and it would be unreason- 

 able not to extend our view to the probabilities derived from other sources of the 

 inferences to which the various hypotheses lead, and which often enable us to select 

 among them. 



For example, in the symbol of the chloride of boron, a'"''':^^|3J+^^, the value of z is 



necessarily limited only by the condition w(/3i)= — — , whence z is less than 5. But if 



we proceed to assign to z the diflferent values 0, 1, 2, 3, 4, it will be found that on the 

 first hypothesis, 2=0, the combinations of the prime factor j3j form a system strictly 

 similar in the laws of their construction to the system of the combinations of the prime 

 factors V, <p, and § ; whereas on the other hypotheses they are analogous to no existing 

 system whatever. 



Thus, putting z=0, we have the following parallel systems, limiting our view for the 

 moment to the gaseous compounds of boron. 



z=0. 



Boron .... 

 Chloride of horon 

 Boric methide. 

 Boric ethide , . 

 Triethylic borate . 



Phosphorus . . 

 Chloride of phosphorus 

 Trimethyl-phosphine 

 Triethyl-phosphine . . 

 Phosphite of ethyl . . 



(aff 



Nitrogen uv* 



Chloride of nitrogen . 

 Methylamine . , , . 

 Ethylamine , . . . . a'vx^ 





Arsenic i'^fT 



Chloride of arsenic . . . a?^ 



Trimethyl-arsine . . . . a'f«' 



Triethyl-arsine .... a'f«* 



If we put z=l, 2, 3, 4, the system of the gaseous compounds of boron appears with 

 the following symbols : — 



Chloride of boron 

 Boric methide . 

 Boric ethide . 

 Triethylic borate 



z=l. 



a«/3V 



z=2. 

 a'/3V 



2=3. 



«=4. 



a«/3Y 



It is doubtless 



to which no parallel can be found among knovni and existing systems. 

 This coincidence cannot be regarded as of an accidental character, 

 the result of the profound analogy of chemical properties by which this group of ele- 

 ments is connected, and which is revealed to us in the similarity of the symbolic forms 

 of their combinations. 



