INSECTICIDE AND FUNGICIDE BOARD. 599 



ates of Calcium. II. P^quilibriiim in the System Arsenic Pentoxide, 

 Calcium Oxide and Water at 35° (Basic Section)" was practically 

 complete. However, when the data were collated and studied it 

 ^yas found that certain fuither work was necessary, which was con- 

 tinued from time to time duriuf? 1922 and will be continued in 1923. 

 This paper covfTrs the region in which there is free lime and practi- 

 cally no arsenic oxide in solution and is consequently of interest to 

 manufacturers of commercial calcium arsenate. It is not known ex- 

 actly when this paper will be offered for publication, since it has bef n 

 necessary to drop work on this subject for the present. The woik 

 will be resumed at the first opportunity. At about the same tine 

 that this paper is offered for publication another paper will also be 

 offered entitled "The Arsenates of Calcium. III. General Prepa- 

 ration and Properties of the Crystallized Salts." The chemical 

 work on this paper, which will describe in detail the preparation 

 and the chemical, optical, and crystallo<j;rai)hic properties of about 

 12 definite calcium arsenates, has been almost completed, but the 

 preparation of the paper will not be attempted until the work on 

 the first paper mentioned in this paragraph is comfjeted. 



An investigation was started during the year to determine the 

 active principles of two species of larkspur seeds {Delphiniutii con- 

 solida and Delphinium staphisagHa) . This investigation was under- 

 taken largely to determine if the oils in larkspur seeds have any 

 insecticidal value, as claimed by some of the manufacturers of 

 human head and body lice preparations. A digest of the literature 

 has been made and a method of extracting and separating the oils 

 and alkaloids on a considerable scale has been developed. This 

 method is now being applied in obtaining a sufficient amount of 

 oils and alkaloids to make a more detailed study of their chemical 

 composition and their action on insects. Work on this subject will 

 be continued during the fiscal year 1923. 



The investigation begun some two years ago to determine what 

 chemical changes commercial samples of calcium arsenate ^undergo 

 during storage has been completed and the results are in process of 

 fjublication as a department bulletin under the title " Chemical 

 Changes in Calcium Arsenate -During Storage." This work was 

 taken up as a result of the belief by certain manufacturers and users 

 of this product that it deteriorated rapidly and was unfit for use 

 after standing for a few months. The work shows that carbon 

 dioxide is very slowly absorbed by the calcium arsenate (or by the 

 calcium hydrate which is present in commercial calcium arsenate) 

 when kept in certain types of commercial containers, resulting in a 

 gradual increase of water-soluble arsenic, which reaches a maximum 

 after about eight months in the case of the most open containers, 

 such as sugar barrels. Material packed in tight containers, such as 

 metal drums or heavy hardwood barrels, showed practically no 

 change after 20 months' storage. In a few cases, where commercial 

 calcium arsenate was stored in veneer drums and sugar barrels, the 

 deterioration at the end of 20 months was such as to render the 

 material of doubtful safety for application on certain plants having 

 tender foliage. 



The study inaugurated some years ago to determine the rate of 

 loss of nicotine in potash-nicotine and soda-nicotine soaps and in 



25684— AGB 1923 39 



