US777669A - Process of producing salts of hydrosulfurous acid. - Google Patents

Description

No. 77?,669. PATBNTED DEC. 20, 1904. A. FRANK.

PROGESS 0F PRODUCING SALTS 0F HYDROSULFUEOUS ACID.

APPLICIATION FILED MAR. a, 1900.

5m MODEL.

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, I wa n UNITED STATES Patented December 20, 190%.

PATENT OFFICE.

ALBERT FRANK, OF CHARLOTTENBURG, GERMANY.

SPECIFICATION forming part of Letters Patent No. 777,669, dated December 20, 1904.

Application filed March 8,1900. Serial No. 7,879,

To all, whom, it may concern.-

Be it known that I, ALBERT FRANK, a sub ject of the King of Prussia, German Emperor, and a resident of 26 Berlinerstrasse, Charlottenburg, near Berlin, in the Kingdom of Prussia, German Empire, have invented a new and useful Process of Producing Salts of Hydrosuli'urous Acid, of which the following is an exact specification.

The present invention relates to an improved process for producing compounds of hydrosulfurous acid by electrolysis according to the following equation:

Already Schonbein has "found that this acid generally results from the electrolysis of acid sulfite of sodium (Journal of Practical Chemistry, 61, 193) and Groult (Com/pt. Renal, 1877, 85, 225) has found the same. Recently Villon (Lima 1 cm .Electriguc, 1890, 30, 231, and 1891, 1 1, 131) and Ekker (Rec. Tree. Obi 1a., 1895) have published articles about the method which, in improved form, is the subject-matter of my invention. In spite of all care taken, for instance, by Villon high outputs of salt with respect to the quantity of current employed never could be attained,

the produced hydrosulfurous acid being easily decomposed again by the further influence of the current or oxidized by the action of the atmospheric air. In order to avoid this decomposition or oxidation of the produced hydrosuliurous acid, I provide my new process, which is based upon the fact that a secondary decomposition of this acid is not to be feared in case as initial product for all compounds of the hydrosulfurous acid salts are produced which are insoluble and deposit during the electrolysis, so that they can easily be removed from the influence of the current.

My process consists in producing the hydrosulfites of alkaline-earth inetals or earth metals by electrolyzing a practically neutral solution of the bisulfite of the respective metal within a casing provided with a diapl'iragm in such manner that the bisullite solution is contained in the receptacle in which the negative electrode is situated, while the positive electrode is situated in diluted sulfuric acid, alkali lye, or

a suitable salt solution--as, for instance, a solution of caustic soda. During the electrolysis, as above described, the hydrosulfite of the earth mctalas, for instance, in case of a practically neutral solution of calcium bisullite (OtLEiaSzOe) being used the hydrosullite of calcium (CaSeOi) deposits at the cathode in form of a heavy soluble crystalline mass. The reation going on during the electrolysis is the following:

CitHaS20t-l- 2 H I (JELSeOr-l- After the electrolysis is completed only a very small quantity of hydrosulfite of calcium remains in the solution. The hydrosullite of calcium deposited at the bottom of the receptacle in which the cathode is situated will not be submitted to a secondary decomposition, as it is no more influenced by the current and does not come in contact with the atmospheric air on account of it being covered by a liquid. The output of salt with respect to the quantity of current is the greater the less acid is contained in the cathode liquid during the electrolysis, and it has proved advantageous to employ as cathode lye asolution of bisuliite of calcium, which, if possible, does not contain more sulfurous acid than corresponds to the formula: GflSOs'l-I'IeSOa.

Equally high outputs are obtained when alkali lye or a solution of such a salt is used as trolysis secretes an alkaline ion, so that the liquid within the cathode-casing remains as other. The cells C are hermetically closed by rubber plugs, through which the conductors F project.

The cathode-cells C are connected to each other by means of tubes G, which pass through the rubber plugs serving for closing. these cells. These tubes G serve the purpose of leading the lye from one cell into the following one. The first cell is connected to the storage vessel A by means of the tube H, and the last cell 0 is connected again by means of the tube J to the storage vessel A, so that the lye flows from the storage vessel through the tube H into the first cell, passes through all the cells, and is led from the last cell C through the tube J back to the storage vessel A. The flow of the electrolyte .in the above manner may be effected by arranging in the receptacle A an ordinary pump-piston P, provided with a valve R, this valve allowing the electrolyte to flow through the same in the downward, but not in the upward direction. By pressing the piston P downward the electrolyte flows through the tube H, the cells, and the tube I back into the storage vessel A into the space above the piston P. If the piston arrives at the bottom of the storage vessel, it is moved upward, so that the liquid passes through the valve R. If the piston arrives at the upper end of the storage vessel, the liquid is situated underneath the same and can be pressed again through the apparatus by moving the piston P downward. It will be understood that any other convenient means for effecting a flow of the electrolyte through the apparatus may be provided. There are, further, tubes K between the different cells C, through which inert gases, as hydrogen or the like, are led through the different cells of the apparatus. The cells C may be provided with liquid-gages L.

Having thus fully described the nature of this invention, what I desire to secure by Letters Patent of the United States is 1. A process for producing hydrosulfites of the alkali-earth metals or earth metals, consisting in bringing a practically neutral solution of bisulfite of the respective metal into the cathode-compartment of an electrolyzing apparatus and electrolyzing the solution under such conditions that the bisulfite solution is kept practically neutral, substantially as described and for the purpose set forth.

2. A process for producing hydrosulfites of the alkali-earth metals or earth metals, consisting in bringing a practically neutral solution of bisulfite oi" the respective metal into the cathode-compartment of an electrolyzing apparatus the anode-compartment of which contains a solution of a compound of an alkali metal and electrolyzing the solution, substantially as described and for the purpose set forth.

In witness whereof I have hereunto set my hand in presence of two witnesses.

ALBERT FRANK.

Witnesses HENRY HASPER, WOLDEMAR HAUPT.

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