MAN AND SCIENCE: A REPLY. 



69 



correspondence in thought or fact. All that has 

 gone before is perfectly familiar ground to the 

 physiologist ; for those who care for further de- 

 tails I subjoin a few tables in a note. 1 But I 

 would not leave this branch of the subject with- 

 out entering a formal protest against the unscien- 

 tific idea of burning fuel on a " local hearth," and 

 finding the resulting heat in " external space." 

 Even to hint at the possibility of such a thing is 

 to ignore all the plain facts and possibilities of 

 physical science. When an external wire is heat- 

 ed by an electric current, the heat in the wire is 

 not the heat which was generated by combustion 

 of zinc in the battery. The heat appears where it 

 is generated (in this as in all other cases), i. e., in 

 the wire itself by its resistance to the free passage 

 of the current, in something of the same way as 

 heat is developed everywhere by resistance of 

 motion — in other words, by friction. That there 

 is a correspondence between the quantities involved, 

 depends upon the most obvious and well-known 

 physical laws. 



1 The following tables indicate several series of ob- 

 servations on muscle contracting under various condi- 

 tions of freedom, and lifting different weights. Each 

 table consists of two columns. One, headed W., rep- 

 resents the amount of external work done, reduced to 

 the centimetre-gramme scale ; the other, headed T., 

 indicates the proportional elevation of temperatu re, as 

 marked in degrees of the arbitrary galvanometer scale. 

 It will be remembered that the greatest elevation here 

 indicated will be but a small fraction of one of our or- 

 dinary thormometer degrees. 



Tables I. and II. and Tables in. and IV. respective- 

 ly represent two sets of observations with two muscles, 

 and with the thermometric scale differently arranged. 

 Tables I. and III. represent the results with the mus- 

 cle fresh in action; Tables II. and IV. correspond to 

 the results with the same muscle fatigued with its pre- 

 vious work. In the latter cases the elevations of tem- 

 perature are not so uniform as in the former. Table I. 

 may be read thus: When the muscle does no external 

 work, but is caused to contract freely, the scale marks 

 an elevation of temperature of 8.5°. When the work 

 is represented by 20, the scale marks 12% and when 

 40, the scale marks 14°. On relieving the muscle from 

 all weight, the scale again marks 8.5°. The others are 

 read in like manner. In all these observations the du- 

 ration of the contraction in seconds was carefully al- 

 lowed for. 



It is assumable that Prof. Tyndall considered 

 his entire argument, and all the scientific illus- 

 trations attached to it, to be " solidary " as bear- 

 ing upon this " burning question " of man's free- 

 will ; therefore, although I do not see the direct 

 application of the following passage, I quote it 

 as affording an opportunity for examining how 

 much science has to say in the matter, and how 

 much fancy : 



" And here we are able to solve an enigma 

 which long perplexed scientific men, and which 

 could not be solved until the bearing of the me- 

 chanical theory of heat upon the phenomena of 

 the voltaic battery was understood. The puzzle 

 was that a single cell could not decompose water. 

 The reason is now plain enough. The solution of 

 an equivalent of zinc in a single cell develops not 

 much more than half the heat required to decom- 

 pose an equivalent of water, and the single cell 

 cannot cede an amount of force which it does not 

 possess. But by forming a battery of two cells 

 instead of one we develop an amount of heat 

 slightly in excess of that needed for the decom- 

 position of the water. The two-celled battery is 

 therefore rich enough to pay for that decomposi- 

 tion, and to maintain the excess referred to within 

 its own walls." l 



In this passage there are two most remark- 

 able divergences from scientific accuracy — the 

 first altogether incomprehensible, the second 

 perhaps due to an over-estimation of the value 

 of a certain hypothesis. It is stated here, as a 

 puzzle or an enigma, that " a single cell cannot 

 decompose water." This might be an enigma 

 ivere it a fact ; but it is a matter of constant ex- 

 perience that one cell does decompose water, as 

 is shown familiarly in the polarization of pla- 

 tinum plates in a voltameter in circuit with one 

 cell. In attempting to measure accurately the 

 electrical resistance of organic tissue, such as 

 nerve, I have lost (or spent) scores of hours in 

 attempting to obviate the exceeding inconven- 

 ience arising from the fact that one single cell 

 did decompose water. For those who wish 

 further confirmation of the fact by independent 

 testimony, I would refer to the article "Elec- 

 trolysis " in the second supplement to Watts's 

 " Dictionary of Chemistry," where ample illus- 

 trations are given. 



The second instance to which I have alluded 

 is the assumption that tho water in a galvanic 

 battery is decomposed by heat. If the term 

 "heat" be used in the non-natural sense, which 

 is now so fashionable, as being synonymous with 

 all motion, all action, all affinity, all change in 



1 Fortnightly Review, November, 1877, p. 599. 



