ELECTRONS 6i 



damaged. When, in the combination of the two 

 gases hydrogen and oxygen, the fluid water is 

 formed, it almost seems that the atoms of the 

 gases are lost and gone for ever ; but by a simple 

 process the water can be decomposed, and the 

 atoms come forth again quite unchanged and as 

 dry as a bone. In a clear lotion of perchloride of 

 mercury, the silvery mercury atoms seem com- 

 pletely abolished, but they are in the clear fluid all 

 the same, giving it weight and certain mercurial 

 characters ; and by suitable means they can easily 

 be produced again. There does not seem to be 

 much black carbon in the bottle of aerated water, 

 and yet it can be demonstrated by ordinary 

 chemical analysis. 



Everything, in fact, seemed to prove the inde- 

 structibility of Dalton's atoms, and of material 

 substance. " Do with it what we please," wrote 

 Professors Stewart and Tait, " we cannot make 

 our senses indicate to us an increase or diminution 

 in a given quantity of what we call matter. We 

 find it so far amenable to our control that we 

 can alter its arrangement, form, density, state of 

 aggregation, temperature, etc. ; nay, by so approxi- 

 mating it to other matter as to produce a chemical 

 combination, we may entirely transform its appear- 

 ance and properties — all hut one ^ its mass or quantity 

 is completely beyond our control. (Measure it by 



