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Adhesion and alloying of electrolytically deposited metals
July, 1914.]
CURRENT TOPICS.
I2 7
Earthquake Construction. A~oN. (Sci. Amer., cx, No.' I I, 227.)--Earthquake construction has now reached a very practical stage in the seismic districts of Italy, where all new buildings are being erected under strict supervision with regard to their ability to resist earthquake shocks. Professor Omori, the Japanese authority, has estimated that 99.8 per cent. of the deaths in the great Messina earthquake of 19o8 would have been prevented if the buildings had been properly constructed.
Increasing Motor Power. ANon. (Sci. Amer., cx, No. II, 227.)--A somewhat original method is used by the Brown-Boveri Works to increase the amount of power which a given electric motor can be called upon to furnish; for instance, where a factory uses a motor rated at 500 horsepower this new method allows of getting considerably more out of it, say 7oo or Boo horsepower. This often makes it unnecessary to put in new motors for the increase of a plant, hence a great saving. The method depends upon the fact that in the induction motor the power factor often has a low value, so that the motor does not furnish nearly so much power for its size as it would were the power factor of higher value or nearly unity. For rolling mill motors, where these are subject to severe strains and overloads at times, the motor must be very much larger than the average power would demand, hence it is an advantage to use a smaller motor for the same power. This is done by a small extra device in the shape of a one-hoi'sepower motor, coupled to a rotating commutator, and this acts to change the value of the power factor and increase the output of, say, a large IOOOhorsepower motor with which it is used. The small device is connected to the circuit of the large motor. Adhesion and Alloying of Electrolytically Deposited Metals. 1VL SCHLOTTER. (Chem. ZAt., xxxviii, 289.)--The degree of adhesion is satisfactorily determined by Burgess's method, in which a copper disc is soldered to the surface of the deposit, the force required to detach the latter from the underlying metal being measured by a spring balancel Several factors influence the degree of adhesion, such as nature and hardness of the deposit and of the cathode metal; generally speaking, a soft metal adheres more firmly to rough surfaces than to smooth ones. The molecular attraction between cathode and electrolyte is increased by the addition of alcohol, which improves some deposits. Several metals occlude.hydrogen during electrolysis, part of which is given off subsequently as gas, which accumulates under the deposit and decreases the degree o f adhesion. In some cases the deposit alloys with the cathode, and the two cannot be separated. Zinc, when copper plated first becomes yellow; the thin coating of brass is subsequently covered with the deposit of copper.
CURRENT TOPICS.
I2 7
Earthquake Construction. A~oN. (Sci. Amer., cx, No.' I I, 227.)--Earthquake construction has now reached a very practical stage in the seismic districts of Italy, where all new buildings are being erected under strict supervision with regard to their ability to resist earthquake shocks. Professor Omori, the Japanese authority, has estimated that 99.8 per cent. of the deaths in the great Messina earthquake of 19o8 would have been prevented if the buildings had been properly constructed.
Increasing Motor Power. ANon. (Sci. Amer., cx, No. II, 227.)--A somewhat original method is used by the Brown-Boveri Works to increase the amount of power which a given electric motor can be called upon to furnish; for instance, where a factory uses a motor rated at 500 horsepower this new method allows of getting considerably more out of it, say 7oo or Boo horsepower. This often makes it unnecessary to put in new motors for the increase of a plant, hence a great saving. The method depends upon the fact that in the induction motor the power factor often has a low value, so that the motor does not furnish nearly so much power for its size as it would were the power factor of higher value or nearly unity. For rolling mill motors, where these are subject to severe strains and overloads at times, the motor must be very much larger than the average power would demand, hence it is an advantage to use a smaller motor for the same power. This is done by a small extra device in the shape of a one-hoi'sepower motor, coupled to a rotating commutator, and this acts to change the value of the power factor and increase the output of, say, a large IOOOhorsepower motor with which it is used. The small device is connected to the circuit of the large motor. Adhesion and Alloying of Electrolytically Deposited Metals. 1VL SCHLOTTER. (Chem. ZAt., xxxviii, 289.)--The degree of adhesion is satisfactorily determined by Burgess's method, in which a copper disc is soldered to the surface of the deposit, the force required to detach the latter from the underlying metal being measured by a spring balancel Several factors influence the degree of adhesion, such as nature and hardness of the deposit and of the cathode metal; generally speaking, a soft metal adheres more firmly to rough surfaces than to smooth ones. The molecular attraction between cathode and electrolyte is increased by the addition of alcohol, which improves some deposits. Several metals occlude.hydrogen during electrolysis, part of which is given off subsequently as gas, which accumulates under the deposit and decreases the degree o f adhesion. In some cases the deposit alloys with the cathode, and the two cannot be separated. Zinc, when copper plated first becomes yellow; the thin coating of brass is subsequently covered with the deposit of copper.