86 OV THE SIGNIFICATION OF CHEMICAL TERMS. 



.^ 



^s composed of an infinite number of minute particles or 

 integrant parts, each of which has precisely the same pro- 

 perties as those that belon<^ to the whole mass.'* For, it is 

 obvious, such integrant parts may either be Dr. Thomson'* 

 particles {of the first order) or Mr. Murray's smallest par- 

 ticles into which a substance can be resolved without decom- 

 position, which I call atoms. Dr. Henry uses the term 

 particles at times in the same inde^nite manner as his pre- 

 decessors. 



NVrrds impro- There are some other current expressions among chemical 

 perly used. . . «» -^ xl ^ -.l i 



writers on affinity, that are either erroneous or misunder- 



Katio. stood. Chaptal says, that " the affinity of composition h 



in the inverse ratio of the affinity of agjjjregation." Dr. 

 Henry has adopted a similar expression, page 53. The only 

 thing that can be intended by this expression is, that the 

 affinity of composition is less efficacious, as the affinity of 

 aggregation is greater; but not the affinity has precisely 

 half the effect, when that of aggregation is double. 



Berth r>llct on Some new opinions and expressions were introduces by 



theefFxtof ]ggrthollet, which want both confirmation and illustration ; 



aflfiniiy, one of them is, that the effect of affinity is in proportion to 



the weight of a body multiplied by the degree of its affi- 

 nity. Mr. Murray, page 85, has it: " the chemical action 

 of any body is exerted in the ratio of its affinity and quan- 

 tity." Dr. Henry observes, page 72, " to obtain a measure 

 of the action of two bodies on a third, if their respective 

 affinities were precisely determined, it would only be neces- 

 sary to multiply the number indicating the affinity by the 

 quantity." BerthoUet's language on this subject would 

 seem to warrant this conclusion as his ; but the experi- 

 ments hie adduces certainly warrant no more than that the 

 effect " is moditied consiclerably by the mass," as Dr. 

 Thomson expresses it. Mr. Murray however has attempted 

 to illustrate the truth of the principle (Appendix, page 19), 

 and' Dr. Henry to explain its meaning (page 72), according 

 to the sense in which they understand it. The latter has 

 succeeded very well; but the former, having a much more 

 difficult task, has, I think, still left some obscurity about 

 it. The explanation is this: *' if a particle of sulphate of 

 barytes be on every side in contact with particles of potassia, 



what 



