The Great Chemist, Josejih Black. 59 



calculated by its specific heat. Of course this reasoning required 

 the whole law of specific heat from ultimate zero to present 

 conditions to be constant, or in an altered form, that this law 

 should at least be known in all its steps. The results to science 

 were not more remarkable than those to be found in another 

 sphere. The steam engine, used chiefly in draining mines, was 

 at that time a very uneconomical tool. For example it is stated 

 that — "an engine having a cylinder of three feet diameter working 

 continually consumes almost 3,000 tons of coal in a year." 

 Fortunately for the world Dr. Black had a friend and pupil or 

 assistant at the time in the person of James Watt, himself an 

 experimentor of supreme merit and an acute reasoner. It is 

 hardly too much to say that to these experiments of Black's, 

 studied, and repeated and varied as they were by Watt, is due 

 much of the great advance made by the latter in the construction 

 of the Steam Engine, more particularly the Separate Condenser. 

 Watt M^as then employed in fitting up the instruments in the 

 McFarlane observatory, and got into his hands a small model of 

 NeAvcomen's steam engine, and we all know the result of the 

 combination of Black's suggestions with Watt's skill and imagina- 

 tion. Curiously enough, but also naturally enough, Black's 

 discoveries reinforced for a time the material theory of heat, so 

 that in 1803 we find Robison lecturing as follows : — "Here we 

 observe another combination of heat or fire, the mighty agent by 

 whose operation all these changes are affected. Heat, or the 

 cause of heat, seems now to put on a real form, and as no longer 

 to be considered as a mere condition or state, into which other 

 matter can be brought, as noise or sound is known to indicate 

 merely a certain undulating or tremulous motion of the air. 

 But we now see heat susceptible of fixation, of being accumulated 

 in bodies, and, as it were laid bye till we have occasion for it, 

 and we are as certain of getting the stored-up heat out of the 

 steam or water, by changing them into water or ice, as we are 

 certain of getting out of the drawer the thing we laid up in it." 

 This remained the common doctrine until 1840, and the singular 



