>42 



NA TURE 



[July 4, 1901 



way, only a compound of nickel is used in place of the com- 

 pound of iron. The method by which these compounds are 

 obtained and their constitution was not described in Dr. 

 Kennelly's paper, but from the patent specification it appears 

 that the compound of iron used is the monosulphide, FeS, which 

 is formed after being made up into the briquettes by electrolytic 

 oxidation in a solution of potassium hydroxide. The superoxide 

 of nickel is prepared in the same manner by electrolytic oxida- 

 tion of the ordinary hydrated oxide of the metal. Cobalt, it 

 is said, can be used instead, but is more expensive. The 

 briquettes of active material are placed in the little nickel- 

 plated steel boxes, a cover is put on, and the boxes are then 

 inserted in the " windows" of the grid. The assembled plate 

 is then subjected in an hydraulic press to a pressure of about 

 100 tons (about i or i4 tons per square inch), thus tightly 

 closing the boxes and, by bending their sides over the edges of 

 the recesses in the grid, fixing them firmly in position and 

 making the whole into a rigid plate. The plates are separated, 

 positive from negative, by thin perforated sheets of hard rubber, 

 and are placed in a steel box which is filled up with the potash 

 solution. The cell is then charged by pas.sing current through 

 it from the nickel to the iron plate, thus oxidising the nickel 

 compound to superoxide of nickel and reducing the iron com- 

 pound to spongy metallic iron. 



It is obviously impossible to say at present how far this cell 

 will satisfy the five conditions already stated. With regard to 

 the first and the last, for example, no data are as yet available. 

 The first is naturally one of the most important considerations, 

 since it is necessary not merely that the cell should have a long 

 life, but that it should not deteriorate too much even when sub- 

 jected to somewhat careless treatment, as it is certain to be if it 

 come into at all general use for motor-cars. Certain experiments 

 which were quoted by Dr. Kennelly lead, however, to the hope 

 that the cell will not be found wanting in this respect. Thus it 



giving five hours' discharge at 42-5 amperes, thus having a capa- 

 city of 213 ampere-hours, or 260 watt-hours. It has, therefore, 

 a capacity of 10 watt-hours per lb. (22 per kilogramme), a figure 

 somewhat lower than that given by Dr. Kennelly in the body of his 

 paper. In an article on accumulators which appeared recently 

 in the Electro-Chemist and Metallurgist (May 1901, p. 116), 

 Mr. J. H. West gives a carefully calculated table of the capa- 

 cities of all the principal accumulators exhibited at the Paris 

 Exhibition or which took part in the .Automobile Club compe- 

 tition of 1899. We can take from this table the figures relating 

 to accumulators having a capacity of 200 ampere-hours and dis- 

 charging in five hours, which are exactly comparable, therefore, 

 with the Edison cell, the discharge curve of which is given in 

 Fig. 2. Calculating from these data we get the results given in 

 the accompanying table; there are 19 cells included in Mr. 

 West's list, but as some of these are heavy cells intended for 

 stationary work, a mean result has been worked out in which 

 the heavier cells are neglected as well as a mean for the whole 

 number. 



Table. 



Watt-hours 

 per kilo- 

 gramme 



Watt-hours 

 per pound 



Mean of all cells in Jlr. West's table 

 Mean of lighter cells ,, ,, 



Lightest cell (Sherrin) ,, ,, 



Edison's cell, from curve 



,, ,, Dr. Kennelly's figures... 



S nOcfiS 



of discharge of Edi? 



was stated that the battery would stand without injury, not only 

 being completely run down, but even being afteiwards charged 

 in the wrong direction. Mr. Edison also states that the nickel 

 plate can be removed from the cell and dried in the air for a 

 week without being injured, and if charged when thus removed 

 will not appreciably lose its charge. The iron plate, if similarly 

 treated, will lose its charge by the slow oxidation of the spongy 

 iron, but will not be in any way permanently injured. 



Perhaps the consideration that appeals most directly to motor- 

 car users is lightness, or large storage capacity per unit weight. 

 In this respect the cell compares very favourably with lead 

 accumulators. According to Dr. Kennelly the storage capacity 

 of the modern lead accumulator is from 4 to 6 watt-hours per lb., 

 or from 9 to 13 watt-hours per kilogramme, whereas the Edison 

 cell is said to have a capacity of 14 watt-hours per lb. (31 watt 

 hours per kilogramme). It will be interesting to examine these 

 figures a little more closely to see whether this claim to an in- 

 creased storage capacity of about 3?; times is in reality justified. 

 We reproduce in Fig. 2 a discharge curve for an Edison cell 

 weighing 25lbs., discharging at 42^5 amperes for six hours. It 

 will be seen that after five hours' discharge the voltage drops 

 from I '45 to I 'o volt ; although it may be possible to obtain the 

 remaining hour's discharge without injury to the cell, yet it is 



As the figures given by Mr. West only 

 refer to ampere-hours, we have assumed 

 in calculating the table that the mean 

 voltage during discharge is i'85 volts, a 

 somewhat low estimate, and one therefore 

 favouring the Edison cell in the above 

 comparison. It will be seen from this 

 table that the Edison cell when compared 

 with the lightest lead accumulator obtain- 

 able is by no means so pre-eminent as 

 regards energy capacity per unit weight. 

 The Sherrin cell, it may be remarked, 

 came very successfully through the Auto- 

 mobile Club's competition, being the only 

 one which did not fall below the specified 

 voltage more than three times during the 

 trials. Although the figures given above 

 may seem to militate against the claims 

 advanced in favour of the new battery, it 

 must be remembered that high storage capacity is not the only 

 advantage that it is said to possess ; even if it were no better 

 than le.ad cells in this respect, if it proves superior to them in 

 the other four conditions it will be a great advance. .\lso it 

 must not be forgotten that the cell is quite new and that no 

 doubt great improvement may be looked for when it is produced 



in large quantities. 



THE BIOLOGY OF MOUNT SHASTA. 

 "T^HE results of a biological survey of Mount Shasta, Cali- 

 fornia, are contained in a BulktiH ' recently received. 

 This publication of 169 pages, with forty-six text illustrations 

 and five heliotype plates, is a worthy successor to its fore- 

 runners, now so well known, and in every respect equal to the 

 best of them. 



It is the result of an investigation by the Biological Division 

 of the U.S. Department of Agriculture under Dr. C. Hart 

 Merriam, chief of the Biological Survey, which svas decided 

 upon in 189S, after the completion of the exploration of 

 southern, middle, and north-east portions of the vast Cali- 

 The great altitude of the mountain (14,450 feet). 



fornian area 

 ery questionable whether this extra energy at so low a voltage , and its position between the Sierra Nevada and the Cascades of 

 as 0-5 volt would be found useful in practice. We are quite \ 1 „ North .'American Fauna," No. 16. U.S. Department of Agriculture, 

 justified in saying, therefore, that this cell is only capable of \ Washington: Government Printing Office, 1899.) 



NO. 1653, VOL. 64] 



