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Improved electric batteries
May,1881.]
Electric Radiometer.
381
Hardening S t o n e . - - D r . Gehring, of Laudshut, Bavaria, has invented an enameling liquid which is said to render ordinary stones and cements harder than granite and to facilitate the imitation of marbles and other valuable minerals. When applied to metals he claims that it will be found an excellent preservative against rust.--Le~ Monde*. C. B ~ g u l a t o r of Vapor P r e s s u r e . - - M . D'Arsonval describes an instrument which he has tested by daily use for more than three years, and which accomplishes the following purposes: 1. To maintain the pressure of any given vapor constant in a boiler whatever may be the supply. 2. To use fuel only in proportion to the quantity of vapor required. 3. To make the actiori of the instrument completely automatic and without danger of explosion.--Comptes Rendus. C. I m p r o v e d E l e c t r i c Batteries.--Azapis has modified the Bunsen cell, using a solution of cyanide of potassium, caustic potash, chloride of sodium or sal ammoniac, instead of dilute sulphuric acid~ thus reducing the consumption of zinc and effecting greater constancy of current. Woehler places a roll of sheet aluminum in a round glass vessel contai~aing very dilute hydrochloric acid or dilute caustic soda. Within this larger roll is placed a porous cell, containing concentrated nitric acid, and a smaller roll of aluminum. Each roll has a lug or projection , which is inserted into a circular cover of ebonite and thus kept in place.--L'Ingen. Univ. C. E l e c t r i c R a d i o m e t e r . - - B e r t i n has repeated before the French Physical Society the first series of his experiments upon the electric radiometer. When the pressure of the air in the radiometer reaches 130 mm. (5"12 in.) the rotation begins, but tt is uncertain; at 90 mm. (3"54 in.) it is decided, but its direction is always determined by some defect of symmetry in the apparatus. At 30 ram. (1"18 in.) it ceases~ but may be produced by a spark or warming one of the tubes; it acts as if a wind blew from the cold to the warm pole. At 15 mm. ('59 in.) the electric rotation occurs alone, and is positive, as if the wind came from the positive pole. At 10 mm. ('39 in.) there is no rotation. From 5 ram. to 2 mm. ('197 to "079 in.) the rotation is negative. From 2 ram. to "2 there is no rotation. At 1 ram. ('004 in.) and less the rotation is always negative, the negative tube being f[uorescent.-- Chron. Industr.
Electric Radiometer.
381
Hardening S t o n e . - - D r . Gehring, of Laudshut, Bavaria, has invented an enameling liquid which is said to render ordinary stones and cements harder than granite and to facilitate the imitation of marbles and other valuable minerals. When applied to metals he claims that it will be found an excellent preservative against rust.--Le~ Monde*. C. B ~ g u l a t o r of Vapor P r e s s u r e . - - M . D'Arsonval describes an instrument which he has tested by daily use for more than three years, and which accomplishes the following purposes: 1. To maintain the pressure of any given vapor constant in a boiler whatever may be the supply. 2. To use fuel only in proportion to the quantity of vapor required. 3. To make the actiori of the instrument completely automatic and without danger of explosion.--Comptes Rendus. C. I m p r o v e d E l e c t r i c Batteries.--Azapis has modified the Bunsen cell, using a solution of cyanide of potassium, caustic potash, chloride of sodium or sal ammoniac, instead of dilute sulphuric acid~ thus reducing the consumption of zinc and effecting greater constancy of current. Woehler places a roll of sheet aluminum in a round glass vessel contai~aing very dilute hydrochloric acid or dilute caustic soda. Within this larger roll is placed a porous cell, containing concentrated nitric acid, and a smaller roll of aluminum. Each roll has a lug or projection , which is inserted into a circular cover of ebonite and thus kept in place.--L'Ingen. Univ. C. E l e c t r i c R a d i o m e t e r . - - B e r t i n has repeated before the French Physical Society the first series of his experiments upon the electric radiometer. When the pressure of the air in the radiometer reaches 130 mm. (5"12 in.) the rotation begins, but tt is uncertain; at 90 mm. (3"54 in.) it is decided, but its direction is always determined by some defect of symmetry in the apparatus. At 30 ram. (1"18 in.) it ceases~ but may be produced by a spark or warming one of the tubes; it acts as if a wind blew from the cold to the warm pole. At 15 mm. ('59 in.) the electric rotation occurs alone, and is positive, as if the wind came from the positive pole. At 10 mm. ('39 in.) there is no rotation. From 5 ram. to 2 mm. ('197 to "079 in.) the rotation is negative. From 2 ram. to "2 there is no rotation. At 1 ram. ('004 in.) and less the rotation is always negative, the negative tube being f[uorescent.-- Chron. Industr.