392 



SCIENCE, 



[Vol. IV., No. 89. 



barbarous. I say this because I believe that the 

 whole — I should not say the whole, but the greater 

 portion — of the causes that have brought the second- 

 ary batteries into such ill repute are due to the vari- 

 ous barbarous practices that have been adopted by 

 those who have been using secondary batteries. And 

 these practices have been indulged in without the per- 

 son knowing the injury they were doing to the battery. 

 The practice has been to dash in a piece of metal in 

 order to see the sparks, and then to say what splendid 

 order the battery was in. A more iniquitous or sin- 

 ful practice could not be adopted. It is just like a 

 doctor cutting off a man's forehead to examine his 

 tongue. Such a practice as that has given the poor 

 battery a straight blow between the eyes, which it 

 will struggle with for days. Any practice that con- 

 stantly calls into action the force of the battery on 

 such a short circuit is simply barbarous, and tends 

 to destroy the battery more than any thing else. I 

 test every cell of my battery every morning with a 

 galvanometer of a hundred ohms resistance. The 

 galvanometer is simply run through on the cells: it 

 takes but a short time, and you can see exactly the 

 condition of the cells without in any way interfering 

 with the condition of your battery. 



There is one point about which I should like to 

 have Professor Dewar tell us a little something. 

 There is one defect, and it is a very peculiar defect, 

 in all of these forms of secondary batteries. It fol- 

 lows, after a short time, from covering the plate with 

 minium, and it is the formation of trees on the plates. 

 That formation is observable in that form and type of 

 battery, and it is not being observed with the Plante. 

 Plante himself has never suffered from the formation 

 of trees ; nor have I, in the batteries I am using, seen 

 the slightest sign of these trees: therefore I think 

 that the mode of separating, to prevent buckling, in 

 my case will be a cure. It will not prevent treeing; 

 and therefore it will not cure that defect, which is 

 one of the most serious defects of the Faure bat- 

 tery. 



Now, I will not say any thing about primary bat- 

 teries. I mentioned, when first speaking, that there 

 had been a good deal of interest expressed about 

 secondary batteries and their introduction; but there 

 has been none expressed about primary batteries. 

 Such a battery as we have to-day has been brought 

 before the London public; and it has been shown 

 that the products of the battery formed in its action 

 will repay the cost of the battery, and that the prod- 

 ucts can be sold for more than they cost: therefore 

 it has been suggested, that, if it be true, it would be 

 a splendid thing for the government to buy up all 

 these batteries, and to use them, and in that way to 

 pay off the national debt. A great many experiments 

 have been made; and the results of these experiments 

 are not to be discarded. They are successfully used 

 for certain purposes, but they are not just yet going 

 to knock out of the field secondary batteries in the 

 way that has been described before us. 



The qualities to which Professor Dewar referred 

 are due to the impurities of the lamp. I have suf- 

 fered somewhat in the same way. I have cured it 



precisely in the same way by putting on the power 

 for twenty hours ; and in that way the impurities, or 

 whatever they may be, have been jostled out. The 

 result has been, that this has had to be done about 

 every two months, whenever there was a repetition 

 of the difficulty. What I am going to do is this: 

 I am going to have my battery in such order that I 

 shall devote one day to the charging of the battery; 

 and my gas-engine will be going all day long, and that 

 will charge up my battery; and I shall have on that 

 day sufficient storage-power to enable me to keep 

 my house lighted for the rest of the week. 



Professor James Dewar. — My views with respect 

 to the chemistry of secondary batteries may be shortly 

 expressed as follows : I feel that, in the future, some 

 other body than the peroxide of lead will be discov- 

 ered, which will more efficiently represent the amount 

 of energy absorbed. I take it to be, that, after all, 

 it is the question of the relative efficiency of such 

 batteries which is the real question under discussion. 

 The electrolytic action is, after all, the question we 

 are to discuss. Now, it seems to me, apart altogether 

 from the difficulties of local action, the question is 

 whether any other chemical bodies likely to be formed 

 during electrolysis will be as efficient as the peroxide 

 of lead in the construction of secondary batteries. 

 Let us take the case, then, of the type of these reac- 

 tions. In ordinary cases of chemical action, we have 

 often two actions taking place. Take, as an illus- 

 tration, the formation of chlorate of potash. As a 

 matter of fact, in this case an exothermic and an 

 endothermic action take place side by side. The 

 total action takes place, like the majority of chemical 

 actions, with a considerable evolution of heat; but 

 the evolution of heat is, in this case, due to the for- 

 mation of the chloride of potassium, and not to the 

 formation of the chlorate. A chlorate would be en- 

 dothermic, would be minus, or there would be a 

 reduction of the temperature during the production 

 of such bodies : therefore the energy for the forma- 

 tion of the chlorate is really in some miraculous way 

 extracted out of the energy produced by the direct 

 formation of the chloride of potassium. The pro- 

 duction of peroxide of hydrogen during electrolysis 

 resembles that of the chlorate of potassium. It is 

 endothermic, formed with a considerable absorption 

 of energy, and consequently can decompose into 

 water and oxygen again with an evolution of heat. 

 If we could construct a battery in which all the oxy- 

 gen is fixed in this way in an unstable body, there is 

 no question but we could produce by this means a 

 much higher electromotive force in secondary bat- 

 teries. If we take the case of electrolysis of salts, 

 we know very well, that, in a great majority of salts 

 used for ordinary purposes, the electromotive force 

 is practically constant, while that accords with the 

 well-known fact, that the thermal value of the for- 

 mation of the majority of soluble salts is nearly in- 

 dependent of both the acid and the base; that is to 

 say, it is nearly constant, giving something like fif- 

 teen thousand gramme units per equivalent. For a 

 direct battery, therefore, comprised of soluble oxide 

 and soluble acid, the electromotive force is practically 



