I04 



SCIENCE. 



[Vol. XL No. 265 



were graduated. In the United States alone, in 1882-83, out of 

 every 1,000 matriculates, '331 were graduated, while in 1886-87 

 only 305 out of every 1,000 matriculates were graduated. 



The Future of Medical Graduates. — Of some one 

 thousand graduates from collegiate institutions, says the Pacific 

 Record, seventy-five only make for themselves a name and promi- 

 nence in their calling. About two hundred, having business quali- 

 fications, become rich by their practice and by judicious invest- 

 ments. Four hundred abandon, in whole or in part, their profession 

 for some more lucrative business ; and the balance struggle with 

 mediocre ability for a bare subsistence, and a wearying effort to keep 

 up an appearance before the people. 



Alcohol and Fevers. — Dr. Kretzschmar of Brooklyn read 

 a paper at the recent meeting in Albany of the New York Medical 

 Society, on the use of alcohol in certain forms of fever. He be- 

 lieved that in some diseases alcohol, if properly administered, was 

 not only instrumental in prolonging life, but was frequently a most 

 potent factor in preserving it. Alcohol possesses the qualities of 

 both food and medicine. It is one of the best antiseptics, and the 

 most reliable remedy we have in the treatment of diphtheria. He 

 regarded alcohol as beneficial in the treatment of phthisis, espe- 

 cially when the temperature of the patient was increased. In the 

 discussion which followed. Dr. Castle advised that stimulants be 

 kept in several small bottles, as, when e.xposed to the air, they lost 

 valuable medicinal properties. 



Bovine Tuberculosis. — Dr. Brush of Mount Vernon discussed 

 at the Albany meeting the subject of bovine tuberculosis. Of all do- 

 mesticated animals, the bovines are the most subject to tuberculosis- 

 Five per cent of the cattle in England are affected with tuberculosis, 

 and it is said that twenty per cent of the cattle in some of the 

 thoroughbred Jersey herds in the Northern States are similarly 

 affected. He believed that more human beings were not infected, 

 because the normal temperature of the human race was so much 

 lower than that of the bovine, — 98.5°F. in the one, and 101° to 

 103" F. in the other ; this latter temperature being necessary 

 for the growth of the germ of the disease. The cultivation of 

 tuberculosis in animals confirms this view, as resistance to the dis- 

 ease decreased as the normal temperature of the animal increased. 

 Thus, in the dog, resistance was good, while in the common fowl 

 it was 7iil. Dr. Brush thought that the Federal Government would 

 do better to spend its money in the investigation and suppression 

 of this disease, than to appropriate five hundred thousand dollars 

 to stamp out pleuro-pneumonia, which did not affect the human 

 race. He believed, that, if bovine tuberculosis were eradicated, it 

 would soon become eliminated from the human race, and he thought 

 that physicians should strive to procure laws which would accom- 

 plish this. 



ELECTRICAL SCIENCE. 

 Secondary Batteries. 



It has been for many years the dream of inventors to perfect 

 some apparatus by which energy could be stored, to be used when 

 occasion required. The secondary battery accomplishes this better 

 than any thing else that has been invented, but it has limitations 

 and defects that it is well to point out. 



The two principal uses, with a great number of minor applica- 

 tions, to which secondary batteries can be put at present, are the 

 distribution of energy for electric lighting, and their use in driving 

 street-cars. As for the first of these, it is well known that the direct 

 system of constant potential distribution cannot be employed at any 

 considerable distance from the central station, owing to the heavy 

 investment in copper necessary. If storage-batteries could be eco- 

 iiomically used, however, they could be distributed at different 

 points through the district, to be lighted and charged by a high 

 potential current, allowing comparatively small conductors to be 

 used, and employing the electric plant during the day, when it 

 would otherwise be idle. 



The advantages for street-car work are apparent : each car carries 

 within itself the energy necessary for running it ; a break-down of 

 one car does not affect the rest of the system. Compared with 

 other electrical systems, the advantages are, that it can be used in 

 crowded streets with no danger from high potential currents ; and 



where a large number of cars are used, it is much simpler than any 

 other plan. Compared with cables, it gives a greater economy of 

 power, a less first cost, and the impossibility of one accident dis- 

 abling the whole line. 



The disadvantages of secondary batteries are the cost, the waste 

 of energy, the deterioration, and the weight for a given capacity and 

 rate of discharge. 



The type of storage-cell most generally in use is some modifica- 

 tion of the Faure cell, generally of the Faure-Sellon-Volkmar type. 

 In it the plates are made of cast lead supports or ' grids,' into which 

 is pasted a mixture of red lead and sulphuric acid. The 'grid ' has 

 in it square hour-glass shaped holes, the contraction in the middle 

 being intended to prevent the active material from falling out. The 

 plates pasted with red lead are put into dilute sulphuric acid, alter- 

 nate plates are connected together, and an electric current is sent 

 between the two sets, changing them into pure lead and lead per- 

 oxide. Plates thus 'formed ' are put into cells with dilute sulphuric 

 acid, a number of lead or negative plates, and peroxide or positive 

 plates, in each cell. This is, verj' briefly, the general method of 

 manufacture. 



Now, suppose we have one of these cells fully charged, — all of 

 the positive plate peroxide, all of the negative plate lead, — and dis- 

 charge it through a resistance. At first the electro-motive force is 

 over 2 volts. This will rapidly run down to about 1.95 to 2 volts, 

 where it will remain constant (provided we do not discharge the 

 cell too fast) for a considerable time, when it will begin to fall, and, 

 if we continue the discharge, it will finally become zero. If, now, 

 the plates be analyzed, it will be found that the positive plate has 

 in it peroxide and sulphate of lead, the latter perhaps fifteen to 

 twenty per cent of the whole active material. The negative plate 

 will consist of pure lead and sulphate. If we charge the cell, the 

 plates will be changed to pure lead and peroxide again, the electro- 

 motive force will gradually rise to 2.25 volts, and, when the charge 

 is nearly complete, oxygen will be given off from the positive plate. 

 There are two very important things to be noticed. If we charge 

 and discharge the cell a number of times, we will find that the en- 

 ergy we get out of the cell is less than the energy we put in by an 

 amount that varies with the rate of discharge, the efficiency being 

 less as the discharge rate is greater : the average efficiency for the 

 present storage-cell is something near seventy per cent. Another 

 point even more important than the first is, that, if we greatly in- 

 crease the discharge rate, the electro-motive force of the cell will 

 fall rapidly ; and if we persist in this, the plates will corrode and 

 buckle, and the plugs of active material will fall out of the holes in 

 the plates. There is one more disadvantage besides these, and 

 that is the fact that the life of the cell, especially that of the positive 

 plates, is limited. Under favorable conditions, the positive plates 

 will last, on the average, two years : the negative plates will last 

 much longer. 



For lighting, the most important disadvantages are the cost, the 

 loss of energy, and the deterioration. The fact that the cells can- 

 not be discharged at more than a certain rate does not greatly affect 

 their usefulness in ordinary cases. And storage-batteries have 

 reached such a state of development that it is safe to say, that, if 

 they were sold and repaired at reasonable prices, they would have 

 at once a great field of usefulness for electric lighting, even with 

 their present defects. The principal cost of a storage-cell is for 

 material : the cost of the labor is comparatively small, and, when 

 the plates have given out, at least a part of the material is left. 



But for traction-work the greatest disadvantage is in the slow 

 discharge rate permissible. At present from three thousand to 

 four thousand pounds of storage-batteries are required to drive an 

 ordinary car, the storage capacity being enough for a run of from 

 forty to sixty miles. This great weight increases the power neces- 

 sary to run the car, the wear of the track, and the deterioration of 

 the car. Besides, it means a considerable first investment, and a 

 large battery to be kept in repair. If we could discharge the bat- 

 tery at any rate we wished, we could make a round trip with seven 

 hundred and fifty to one thousand pounds of battery. We would 

 have to charge our batteries oftener, of course, but we would greatly 

 decrease our items of first cost, depreciation, wear of road-bed and 

 cars, and even of power expended. 



It has been variously estimated that the difference of expense be- 



