Dr. E. J. Mills on the First Principles of Chemistry. 5 



are placed together in such conditions as to react chemically, 

 various kinds of work are performed, and other substances are 

 found to be present. Direct contact is not always necessary ; 

 it may suffice that a shock or tremor traverse the intervening 

 or diachemic medium, in order to produce the desired result. 

 This is well seen in the experiments of Abel and others, where 

 nitroglycerine, gunpowder, and the like have been fired with- 

 out such contact, by the effect of distant explosions of parti- 

 cular quality. 



Continuity is, moreover, observed in the relation of the 

 masses of the acting substances. According to the evidence 

 we possess (and some of it is of the highest order of accuracy), 

 no matter what may be the masses of the substances reacting, 

 the entire mass of each takes part in the process. If we immerse 

 an ounce of zinc in water, and add to it a quantity of hydric 

 sulphate, the whole of this reagent acts, whether it weigh an 

 ounce, a pound, or a hundredweight ; and it is known by ex- 

 periment that if water, zinc, and hydric sulphate be placed in 

 contact, the rate, amount, and quality of the action all depend 

 on a cosmic law — the masses of the acting system — and vary 

 as these vary*. Of this rich and indefinitely great variety of 

 process, the Daltonian symbols show us but a poor and single 

 point, — 



Zn + H 2 S0 4 = ZnS0 4 + H 2 ; 



all the hydric sulphate that is not required to make zinc sul- 

 phate, though undeniably sharing chemically in the process, 

 is omitted from the expression ; and it may be added that the 

 equation itself, one of the most frequently written in books and 

 memoirs, has never yet been realized in the history of che- 

 mistry. May I suggest to those students who are seeking sub- 

 jects for investigation, how much more profitably their time 

 would be employed in examining the commonest definite equa- 

 tions, than in such enterprises as trying to find out by experi- 

 ment what is the position of the third bromine atom in tribro- 

 mobenzol ? 



(7) The mind of Berthollet was clearly impressed with the ne- 

 cessity of reconciling the laws of chemistry with those of astro- 

 nomy. As he contemplated the evening sky and watched the 

 marshalling of its glorious host, no thought of atoms rose (as 

 in Dalton) with those distant clusters ; but the conviction that 

 the earth's laws are not discrete from those of heaven, and that 

 the principle of celestial attraction must be identical with, or 

 animate, the chemical process. The law of chemical mass, 



* For the demonstration in the case of gases, see Bunsen's ' Gasometrv/ 

 p. 254 (English edition). 



