278 Progress in Science. [April, 



is, therefore, useless to discuss the reasoning until these are proved false. The 

 rest of the paper refers more immediately to the conversion of heat and 

 chemical action into mechanical effect. It will be amusing to anyone con- 

 versant with the subject to observe how, in the second paragraph, Mr. Highton 

 gravely sets forth the elementary deductions of thermodynamics as anomalies. 

 That stretching a wire, within the limits of its elasticity, cools it, follows from 

 the fact that heat expands it. A little further on, we find a confusion of energy 

 with the availability of energy, or, as Tait calls, the tutrqby : " TherAJs >ust 

 as much mechanical energy in a lump of ice which -will produce' »ioo units of 

 cold as there is in a lump of coal which will produce 100 units of heat ; there 

 is as much stored up power in a glacier as in a coal-mine." . . ,. "No 

 amount of heat in a body can produce any effect till that body comes into 

 contact or communication with some other body either hotter or colder than 

 itself." If Mr. Highton will refer to Professor T ait's " Thermod}mamics," or 

 Professor Balfour Stewart's " Heat," for the second law about reversible 

 engines, he will see in what way a cold refrigerator is not exactly a source of 

 mechanical energy, but a means of converting more energy already existing as 

 heat into the form of visible motion than we otherwise could; the glacier 

 Mr. Highton proposes to use would be not a source of energy itself, but might 

 serve to render the energy existing as heat around us available. He proceeds : 

 " So that, in reality, force is produced, not by heat or cold, but by the restora- 

 tion of equilibrium in the heat of two bodies, or parts of bodies, unequally 

 heated, and mechanical energy produces neither heat nor cold (except acci- 

 dentally), but simply a disturbance of the equilibrium in the heat of two bodies, 

 or parts of a body." I may just point out that we are not talking about force, 

 but about energy or work. I admit we cannot transform heat into force any 

 more than into yards; there is no more an equivalenfof heat in pounds weight 

 than in pints, though there is in foot-pounds ; but a foot-pound is not a force. 

 This confusion of work and force is common in Mr. Highton's writings. It 

 produces a serious error in his paper in the " Chemical News," of January 27th, 

 which is repeated in the note at the end of the paper in last quarter's 

 " Journal." He then assumes that, if the 'forces in operation in an engine are 

 greater, the engine will necessarily produce more work from the same 

 quantity of fuel. But I presume that, in this case, though the reverend gentle- 

 man says force, he means work. Now, though to change heat into work, we 

 need to have a source and a refrigerator of different temperatures, yet, of the 

 heat which leaves the source, only part ever reaches the refrigerator, the 

 difference disappears as heat, and is changed into the equivalent amount of 

 work. What is meant by mechanical energy producing heat accidentally, I 

 fail to comprehend. Possibly, when the theory which shall replace the science 

 of Thermodynamics is set forth, all cases of failure will be referred to the 

 chapter of accidents, and the theory will have mainly to be proved by its 

 exceptions. But the fact that mechanical energy may be transformed into 

 heat was proved long ago, beyond dispute, by Davy's well-known experiment, 

 in which he melted two pieces of ice by rubbing them together in an atmosphere 

 itself below the freezing point. In paragraph 7, we have — " A given amount of 

 heat applied to expand air will raise ten times the weight that it will if applied 

 to expand vapour of turpentine, and one and a quarter times as much as if it 

 were applied to expand steam. It may be answered, ' Yes ; but it also 

 expands the vapour of turpentine or water, as well as raises the weight!' 

 True ; but this is not mechanical energy as measured by foot-pounds raised ; 

 and to assume that it is equivalent to it, is to beg the question at issue." I 

 think Mr. Highton makes more than one mistake here. His premises are 

 loosely stated ; and even if they had been right, his conclusion would not 

 follow from them. By proper mechanical appliances, such as hydraulic 

 presses, we may make a given amount of heat raise almost any weight we 

 please, whether it be applied to heat air, steam, or vapour of turpentine ; but 

 let us suppose that instead of " raise ten times the weight," it were written 

 " do ten times the work." The specific heat of vapour of turpentine is just ten 

 times that of air; so that we may conclude that Mr. Highton means that it 

 will require ten times as much heat to expand a given volume of turpentine by 



