High Efficiency. at the Cathode, Hydrogen Separated by ?Ltration, The
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Talented Dec. , T24. v STEWART JOSEPH LLOYD, OF ‘UNIVERSITY, AND ABSALOM MASON KENNEDY, OF . MONTGOMERY, ALABAMA. ' - METHOD OF MAING SENICAL SALTS. No Drawing. Application ?led May 22, 1928. Seriall No. 640,786. _ To all whom it may concern: v11.98 parts, by weight, of AszOl8 with from 240 Be it known that we, STEWART J. LLOYD to 250 parts" of NaOH. I - v and ABsALoM M. KENNEDY, citizens of the This solution is then made the electrolyte United States, and ‘residents, respectively, of‘ in an electrolytic cell having insoluble elec- . 5 University, in the county of Tuscaloosa and trodes of any convenient material such as of State of Alabama, and of Montgomery, in iron. ’ the county of Montgomery and State of ' When used without'a diaphragm between " Alabama, have invented a new and Im the electrodes, that is a single solution cell, proved Method of Making Arsenical Salts, with tri-sodium arsenite as an electrolyte,” 10 of which the following is a full, clear, and we have found that the passage of the elec exact description. _ tric current oxidizes this solution to the ar This invention relates to the manufacture senate form (Na3ASO4) at the anode with a of'arsenical salts and especially to the arse high efficiency. At the cathode, hydrogen . nates of calcium and of lead used as insecti is given oil? and we have found that a small 15 cides and has for its object the oxidation of a amount of metallic arsenic is reduced from soluble arsenite (as sodium arsenite) to the the solution, appearing in the solution as corresponding arsenate (as sodium arsenate) small, black articles. from which insoluble arsenates of other With a diap ragm between the electrodes, bases may be prepared. , ' using a solution of tri-sodium arsenite in the 20 It is well known in theart that the princi anode compartment and a solution of sodium pal arsenic com ound of commerce, that is hydroxide in the cathode compartment, the 75 the form in WhlCh arsenic can be the most reduction of metallic arsenic is revented. readily and cheaply rocured, is arsenic The electrical e?iciency of this cc is how trioxide (AszOs) also nown as white ar-v ever less than that of the. single solution cell. 25 senic or arsenious acid and that this oxide The soluble arsenate solution ‘thus pro forms the basis from which the other salts duced is ?ltered to remove any metallic ar 80 - of arsenic are produced. It is also known senic and is converted into the insoluble that arsenic trioxide ma be oxidized to ar insecticides of commerce in the usual man senic pentoxide (As,O5 , as by means of ner, that is by adding the arsenate solution no nitric acid or of chlorine, and that under to a solution or a suspension'containin the suitable conditions the salts of arsenious- acid desired base element and ?ltering, was ing, called arsenites may be oxidized to the cor drying and pulverizing the resultant precipe responding salts of arsenic acid called arse itate. For example, if calcium arsenate is nates, and that the latter salts of certain desired, the soluble arsenate solution, after 35 bases, such as calcium arsenate and lead ar ?ltering, is added to a solution of a soluble senate form the more valuable insecticides calcium salt as the chloride or to a suspen 90 because they are less soluble in water and sion of a less soluble calcium salt as the hy therefore less liable to injure or “burn” the droxide in such proportion as will produce foliage to which they are a plied. In this the desired insecticide. If calcium hy 40 invention, therefore, a furt er' object is to droxide is used, the mixture will separate f convert arsenic trioxide into a soluble arse into a precipitate of calcium arsenate and a 95 nate from which the usual commercial in solution of sodium hydroxide which may be secticides as calcium arsenate or lead arse separated by ?ltration, the solution being nate may be produced. utilized to prepare fresh sodium arsenite 45 To accomplish this we make a soluble ar solution by the addition of AS203 and the senite solution by dissolving arsenic trioxide ?ltrate washed, dried and pulverized. 100 in a solution‘ of a salt of‘ an alkali‘ metal While sodium arsenite has been taken as such as sodium carbonate or hydroxide and an example of a salt which may be used in as the most valuable insecticides usually con this process, it will be understood that other 50 tain as high proportion of the base element soluble arsenites may be .used without de-' .as possible, we prefer to use the hydroxide. parting from the spirit of this invention. We have found it desirable to mix the in Having thus described our invention, what gredients in such proportion that the solu we claim is: 1 _ tion is neutral or slightly basic as by mixing 1. The method of making arsenical salts 1,517,516 which consists in the oxidation of an arse of an insoluble arsenate by the mixing of nite to the arsenate form by electrolysis. ‘ this solution with a solution or a suspension 2. The method of making arsenical salts of the salt of a base producing such insoluble which consists in the oxidation of a soluble arsenate, the separation of the resulting pre arsenite to the arsenate form by electrolysis. cipitate from the solution and the utilization 3. The method of making arsenical salts of this solution. which consists in the production of an alkali 9. The method of making arsenical salts metal arsenite solution and the oxidation of which consists in the oxidation of a soluble this to an arsenate by electrolysis. / ~ arsenite to the arsenate form by electrolysis, 10 4. The method of making arsenical salts, the arsenite solution bein made the anolyte. which consists in dissolving arsenic trioxide 10.- The method of ma ing calcium arse in the solution of an alkali metal salt, and nate which consists in the production of a solution of sodium arsenite by dissolving the oxidation of the resulting solution to 50 I an arsenate by electrolysis. arsenic trioxide in a solution of sodium 5. The method of making arsenical salts hydroxide,the oxidation of this solution to which consists in dissolving arsenic trioxide sodium arsenate by electrolysis and the mix is the solution of an alkali metal hydroxide ing of this solution with the solution or sus pension of a suitable calcium salt. and the oxidation of the resulting solution 55 it. an arsenate by electrolysis. 11. Themethod of making calcium arse a The method ofmaking arsenical salts nate which consists in the production of a which consists in dissolving arsenic trioxide solution of sodium arsenite by dissolving in a solution of sodium hydroxide and the arsenic trioxide in a solution of sodium oxidation of the resulting sodium arsenite to hydroxide, the conversion of this into sodium arsenate by electrolysis. sodium arsenate by electrolytic oxidation, 60 7. The method of making arsenical salts the mixing of this solution with a solution which consists in the oxidation of a soluble or a suspension of a calcium salt in suitable arsenite to the arsenate form by oxidation proportions to form the desired insecticide, in an electrolytic bath and the preparation the separation of the recipitate of calcium of an insoluble arsenate by the mixingof arsenate from the so ution of sodium hy 65 30 this solution with a solution or a suspension. droxide and the utilization of this solution of the salt of a base producing such insoluble in the preparation of new sodium arsenite arsenate. solution whereby the process may be con 8. The method of making arsenical salts tinued. which consists in the oxidation of a soluble 35 arsenite to the arsenate form by oxidation STEWART JOSEPH LLOYD. in an electrolytic bath and the preparation ABSALOM MASON KENNEDY" .