386 



SCIENCE. 



[Vol. IV., No. 



There are many facts connected with the working 

 that I should have liked to give you. I should have 

 liked to give you the efficiency. I have made care- 

 ful experiments as to the efficiency of the storage 

 up to the present time. The cost is certainly within 

 the reach of every man in this room. Every single 

 man in this room can afford the comfort which this 

 light will give him; and an electric plant will enable 

 him to live four or five years longer in this world 

 than he would without the electric light. 



Prof. W. H. Harkness. — I was very much pleased 

 and gratified at hearing Mr. Preece's remark as to 

 the use of secondary batteries. After all that has 

 been said on both sides, it is gratifying to find that 

 we have a certain and valuable method of lighting 

 which is effective and economical. I wish also to 

 add my testimony on one or two points which Mr. 

 Preece has mentioned, and that is, to the courtesy 

 uniformly shown by Mr. Plante to any one who visits 

 him at his laboratory. I had the pleasure, with some 

 friends, of visiting his laboratory, witnessing many 

 experiments made with a large number of secondary- 

 battery cells. As we all very well know, his invention 

 has resulted in the adoption, not only of those second- 

 ary cells, but also of the cells themselves. The use to 

 which he has put them, however, has led to many 

 absolutely new experiments, so far as I know. It is 

 also a point of interest to know, as probably some 

 of you do know, that Plante himself tried a method, 

 many years ago, of covering the plates with minium. 

 If Professor Barker were here, he would bear witness 

 to the fact that Plante has used both; that he tried 

 the same thing several years ago, and found that it 

 was not so effective as a battery of his own plates by 

 the method adopted, which, though necessarily slow, 

 probably resulted in a better form of cell. So it is 

 gratifying to know, from the experiments of Professor 

 Preece, that we are advancing, so far as new experi- 

 ments are concerned, and that we are finally going 

 back to the original form devised by Plante. 



There may be one reason worth mentioning. We 

 are all well aware of the careful and interesting 

 experiments referred to by Mr. Bright, on the chem- 

 istry of the secondary battery. These experiments 

 show us that there is a greater or less formation 

 of the lead sulphate in connection with the cell 

 adopted; and that also shows us why the electro- 

 motive force, having run down, after a period of rest, 

 is recovered to a certain extent. A great many 

 points have been cleared up that were certainly quite 

 enigmatical before. Now, some experiments, and I 

 think some of those that have been published by 

 Professor Barker, go to show, that, in the Plante 

 cell as formed by Plante, — by a rather slow and tedi- 

 ous process, but by the method of Plante, — there is 

 at least a small amount of lead sulphate produced. 

 I take it that the giving-out of the cell is due to 

 the formation of sulphate; so that, if these cells are 

 formed by the rules laid down by Plante", they will 

 have a tolerably long life. Now, just one word with 

 regard to the cost. You will remember that a year 

 or so ago Professor Langley showed, I think beyond 

 any question, that the percentage of . the radiant 



energy from an Argand gas-burner that is effective 

 in producing illumination is less than one per cent. 

 It certainly is a very curious result. It is less than 

 one per cent, and there is little doubt about the 

 energy which goes up through the chimney. 



Mr. N. S. Keith. — Plante was evidently far ahead 

 of his time. He produced what is to-day found to be 

 of vast practical importance. In 1860 or 1861, about 

 the time of his published experiments, there was no 

 electric lighting; certainly none as it exists to-day. 

 There were then electric-lighting men who were far 

 ahead of their time; but it is only within the past 

 four years, we may say, that we have had any possible 

 application of the secondary battery. I am led very 

 forcibly to consider this point, because in 1878, during 

 the experiment I was then carrying on in the elec- 

 trolysis of lead, and in collateral experiments which 

 relate to the chemical action of lead in various sol- 

 vents and in various electrolyses, I was led to make a 

 secondary battery after having made one of Plante's. 

 I made one by coating the plates with peroxide of lead 

 by electro-deposition — not peroxide of lead formed 

 from the substance of the plate itself, as by Plante*; 

 not by coating the lead plate with oxide of lead, or 

 peroxide of lead, as the case may be, from external 

 sources ; but by coating it by deposition from a solu- 

 tion of lead in which the plates were immersed. I 

 took two hundred and forty cast pieces of lead plate, 

 each one foot square. I divided them into ten cells, 

 making twenty-four plates of each cell, twelve of 

 which were positive, and twelve negative. By using 

 a suitable solution of lead (a sub-acetate of lead in 

 nitrate of sodium), and by treating that with a cur- 

 rent of electricity, I produced decomposition of the 

 solution, deposition of peroxide on the positive plate, 

 and at the same time metallic lead was deposited upon 

 the negative plate in a very finely divided and crys- 

 talline state. Some hydrogen is also deposited with 

 the lead, — an equivalent to the oxygen that is depos- 

 ited in chemical combination with the lead upon the 

 positive plate. These plates, after pressing the me- 

 tallic lead so as to cause it to cohere and adhere to 

 the plate, were taken from this solution and immersed 

 in sulphuric acid, and gave a very satisfactory sec- 

 ondary battery indeed. At that time (in May, 1878) 

 I ran a dynamo as an electric motor with this bat- 

 tery, and I effected some chemical and electrolytic 

 decompositions in a solution of sulphate of copper, 

 and did some other things which were then the only 

 possible commercial applications of secondary bat- 

 teries. Since that time, electric lighting by incan- 

 descence has come to the front, and we find the great 

 use of secondary batteries which has been so forcibly 

 set forth by Professor Preece. At that time we did 

 not have telegraphy by the dynamo ; but we had teleg- 

 raphy by the use of the primary batteries with which 

 we are all so familiar. I have since that time carried 

 on a considerable number of experiments relating to 

 secondary batteries. The whole subject is an electro- 

 chemical one. There is a chemical decomposition of 

 the solution by the passage of a current of electricity. 

 There is a decomposition of the water of the elec- 

 trolyte either primarily or secondarily. Oxygen goes 



