56 



SCIENCE. 



[Vol. XII. Nc. 2S7 



lower than 75" F., and here either placed on shelves or piled one 

 on the other on the floor. In some cases the rice is sprinkled with 

 waterand left standing in baskets several hours before it is distributed 

 on the trays. In other cases the trays are not placed in the warm room 

 until toward evening of the second day (the day after sowing the 

 ' tane '), and they are then left undisturbed until early in the morn- 

 ing of the third day. When the rice is not moistened the trays are 

 left standing only four or five hours, when the contents of each 

 must be thoroughly stirred by hand, which process is repeated after 

 another four hours of rest. At this stage the fungus grows rapidly 

 and much heat is evolved ; the grain becomes opaque, assuming 

 a fibrous texture and becoming somewhat sour in taste. After 

 from four to ten hours the trays are emptied of their contents and 

 the rice spread thinly on mats to cool. It is then ' koji.' 



There is a loss of weight during the process of from ten to twelve 

 per cent of the rice used. This is due to the evolution of carbonic 

 acid, which makes the ventilation of the room necessary in order to 

 make it possible for the men to remain in it. The usual mode of 

 ventilation is to insert a perpendicular flue, which can be opened or 

 closed at pleasure, extending from the ceiling to the outside air, 

 and an inclined or horizontal flue which discharges fresh air near 

 the floor. 



ELECTRICAL SCIENCE. 



A New Diffusion Photometer. 



Mr. J. JOLY has brought out a new photometer which is simple 

 and sensitive. One form consists of two parallelepipeds of paraffin 

 of equal dimensions, planed smooth so they can be laid accurately 

 together on similar faces. Putting these together with the plane of 

 discontinuity at right angles with the line joining the lights to be 

 compared, the compound block is moved toward one or the other 

 of them until the fine line of division between the two pieces al- 

 most or wholly disappears. The distances from the lights to the 

 plane of discontinuity are now measured; and the relative intensi- 

 ties reckoned as inversely as the squares of the distances. In the 

 case of lights of dissimilar colors the appearance of the photometer is 

 no longer uniform, but that of two softly glowing substances of 

 different colors. Even under these circumstances, if the colors are 

 not greatly different a point of minimum distinctness of the line 

 can be found with considerable accuracy. The greater sensitive- 

 ness of this photometer over some of the other forms used is due to 

 the fact that we have to concentrate all of our attention on the line 

 of junction only, not on two images at some distance apart. In- 

 stead of paraffin, glass of a transluency approaching that of par- 

 affin may be used, and the effect may be heightened by interposing 

 between the two pieces a sheet of silver foil. The dimensions that 

 Mr. Joly finds best are 20 by 50 by 11 millimetres for each parallel- 

 epiped. They are laid together on two of the larger faces, the 

 parallel external faces being ground smooth, but left unpolished. 

 The surface under observation during the experiment is ground 

 smooth and polished after joining the parallelepipeds. The most 

 important points to be attended to in their construction are fineness 

 of division line and uniformity in thickness. Should there be any 

 difference in the translucency of the parallelopipeds a check observa- 

 tion might be made by turning over the photometer so that the 

 halves change places relatively to the lights, taking the mean of the 

 observations. This is, however, rarely necessary. This compound 

 block is mounted in the same way as an ordinary Bunsen photo- 

 meter, and the same precautions are necessary in using it. 



Electric Traction on the Underground Roads in 

 London. — Nowhere can electricity be more. easily employed for 

 traction work than on the underground roads that are to London 

 what the elevated roads are to New York. The rational method 

 of employing it is to use motors supplied from an overhead wire, 

 the electricity being generated at stations along the lines. The 

 objections sometimes urged against the overhead system for use on 

 city streets cannot apply here, and there would be little doubt of 

 the economy of the system, besides the great advantages it would 

 possess as far as ventilation and comfort went. Instead of using 

 a direct current, however, it is proposed to employ storage batteries 

 on the train. The motors are to have a capacity of 600-horse 

 power, and when one considers the difficulties that have been ex- 



perienced in getting a battery of reasonable weight that will give a 

 maximum output of ten or fifteen horse power for ordinary tram- 

 way work, it would seem that the plan is almost certain to fail. A 

 hundred tons of battery might be sufficient, but with the initial 

 cost of it, its deterioration, and the power that must be expended 

 to draw it, the chances for the economical working of the system 

 are small. 



Transformers Based on Electrostatic Induction. — M. 

 Doubrava has described a method of reducing currents of high 

 potential and small quantity to those of low potential and great 

 quantity by means of electrostatic condensers. He first charges a 

 condenser of comparatively small capacity to a high potential, then 

 disconnects it from his line and discharges it into a condenser of 

 great capacity, thereby lowering the difference of potential between 

 the coatings, and finally he discharges the large condenser into the 

 lamp-circuit which he wishes to feed. By performing this opera- 

 tion fast enough a practically continuous current is obtained in the 

 latter circuit. While the general idea of using condensers for 

 transforming high to low potential currents is not new, and while 

 methods have been proposed which seem as promising as that of 

 M. Doubrava, yet his system has in it some elements of novelty. 

 The difficulty lies in the great capacity of the condensers that will 

 be required. Taking the charges and discharges as rapid as seems 

 practicable; the condensers — supposing the distribution is at 200 

 volts — would have to have a capacity of about 1,000 micro-farads 

 for every horse-power transformed. Now a condenser of 1000 

 micro-farads capacity is enormous, and would be expensive to 

 build and too large to conveniently store. The efficiency of the 

 system would be, probably, very high, bat it would require rotating 

 apparatus of some description, which, with the fact that house to 

 house distribution at high potential would be dangerous, would 

 necessitate the distribution of the low-potential currents from sub- 

 stations. When one tries to imagine a sub-station distributing 

 500-horse power, with a condenser of a capacity of 500,000 micro- 

 farads, the system will seem a doubtful one. 



Alloys for Electrical Resistances with no Tempera- 

 ture Co-efficient. — Mr. Edward Weston has discovered an 

 alloy whose specific resistance is high and whose resistance is not 

 affected by temperature changes within ordinary limits. This is 

 valuable for electrical resistances, and will doubtless have an ex- 

 tended use. The alloy is a mixture of copper and manganese. It 

 may be made from copper and ferro-manganese in the proportions, 

 copper 70 parts, ferro-manganese 30 parts. A still more curious 

 alloy is made from copper 65 parts, ferro-manganese 25 to 30 parts, 

 nickel 2i parts. This possesses the remarkable property of decreas- 

 ing in resistance as its temperature rises, a peculiarity heretofore 

 ascribed to carbon and electrolytes only. This last alloy can be 

 used with ordinary copper^ or German silver coils in such pro- 

 portion as to cause the total temperature co-efficient to be zero. 

 It is to be hoped that these substances will be carefully studied and 

 their properties at high and low temperatures determined. 



Chemical Action in a Magnetic Field. —Since 1881, 

 when Professor Remsen discovered that the deposition of iron was 

 affected by a strong magnetic field, experiments have been tried to 

 determine the nature of the effect of magnetism on chernical action. 

 The latest and most satisfactory contribution on the subject is that 

 of Prof. H. A. Rowland and L. Bell, in the current number of the 

 America7i journal of Science. Their general method was to take 

 two pieces of the metal to be experimented on, put them in circuit 

 with a galvanometer, and immerse them in an electrolyte between 

 the poles of a powerful magnet. The two pieces were covered 

 with wax except at two opposite points, where they were bare, and 

 by changing the shapes of the uncovered portions the condition of 

 their surfaces with respect to the rate of change of magnetic force 

 could be varied. For instance, in the first experiment that was 

 tried pieces of iron were immersed in dilute nitric acid. One of the 

 bare surfaces was flat, the other filed to a sharp point. If there 

 was no deflection of the galvanometer when the circuit of the mag- 

 net was made, there was a sharp throw immediately on making the 

 circuit, the needle then gradually returning to zero and going past 

 to the other side. The throw was in a direction as if the sharp 

 point was copper and the flat surface zinc. When the point was 



