Januaet 18, 1918] 



SCIENCE 



73 



total of one hundred and thirty-two plants, 

 six wilted; while in 1917, out of a total of 

 more than seveu thousand plants, on the same 

 land only two wilted. 



These data will possibly be of some value, 

 especially to the Southern States, where the 

 peanut promises to become a more important 

 crop in the boll-weevil infested districts, and 

 where Sclerotium Bolfsii has already become 

 established as a serious parasite of numerous 

 crops. J. A. McClintock 



ViBQiNiA Truck Experiment Station, 



NORTOLK, Va. 



THE BOSTON MEETING OF THE 



AMERICAN CHEMICAL 



SOCIETY. VII 



Potash recovery from greensand and feldspar 

 and by-products therefrom: H. W. Charlton. 

 The process, stated briefly, consists in digesting 

 greensand, feldspar, etc., with the requisite 

 amount of lime and water at elevated tempera- 

 tures and pressures. The alkali is brought into 

 solution and recovered as a hydrate, and the solid 

 material, which has undergone both chemical and 

 physical change, is filtered off and employed as a 

 binding material in the manufacture of brick, 

 tile, artificial stone and other steam-hardened 

 products. Possessing, as it does, self-cementing 

 properties in addition to those induced by the 

 steam-hardening treatment, it turns out mate- 

 rials which for strength and resistance to climatic 

 conditions are superior to previously known steam- 

 hardened products. Although the reaction may be 

 applied to alkali-carrying silicates in general, it is 

 believed that greensand is economically the most 

 suitable, occurring, as it does, in unlimited quanti- 

 ties, obtainable without blasting or crushing and 

 lying in stratified layers overlaid with a high 

 silica sand. This is particularly fortunate as the 

 overburden may be used with the resulting binding 

 material in making brick, and the cost of mining 

 is materially lessened. In the proportioning of the 

 digestion mixture when using feldspar it is neces- 

 sary to employ an equal weight or more of lime 

 and eight times its weight of water, and to digest 

 at pressures of from 200-250 pounds for from 

 two to four hours. If the amount of water is re- 

 duced below this figure, the alumina in the feldspar 

 appears to cause a reverting action. Fortunately 

 this ia not the case with greensand where the 

 alumina is normally replaced by iron, and a double 

 concentration can be employed. If lime is added 



in excess, there are no bad effects, as it is changed 

 into a plastic sub-hydrate which in itself is a pow- 

 erful binding material. It is undoubtedly true 

 that the cementing material from a feldspar di- 

 gestion is superior to that from greensand, but the 

 cementitious properties of both are much superior 

 to those now used in the production of steam-har- 

 dened products. Feldspar residue could be used in 

 the manufacture of excellent face brick, whereas 

 greensand residue would probably be better suited 

 for the production of court or common brick, 

 roofing, tile, drain tile, sewer pipe, fire-proofing, 

 etc. Probably the most serious problem in the 

 recovery of potash from feldspar is the separa- 

 tion of the soda. When employing greensand the 

 almost complete absence of soda makes it possible 

 to obtain a very pure caustic with one evaporation. 

 Another objection to feldspar treatment is the al- 

 most invariable presence of alkali aluminates in 

 the caustic liquor. It is found that there is not a 

 trace in the greensand liquors. Although caustic 

 alkali or a hydrated carbonate are the usual prod- 

 ucts of the recovery of the potash, other compounds 

 may be easily formed as an end product. The 

 same is true of the cementing material. Its use is 

 not confined to the manufacture of brick. Other 

 products such as tile, artificial stone, insulating 

 material or stucco, are easily produced, and the 

 choice depends on the market. 



Some problems in the metallography of steel: 

 H. M. BoYLSTON. (1) Banded structures in steel; 

 their existence, cause and effect. Banded structure 

 in nickel steel, in high manganese rifle-barrel steel, 

 in shell forgings. Prevention and cure. (2) The 

 hardening of high-speed steel and its relation to 

 composition and performance. The BeUis micro- 

 scopic test for determining best hardening tem- 

 perature. Effect of carbon content. Effect of 

 special elements. Streaky carbides. (3) The an- 

 nealing of carbon steel castings. Eesults desired. 

 Old methods. Present practise. 



The effect of annealing on the electrical re- 

 sistance of hardened carbon steels: I. P. Park- 

 hurst. The object of the investigation was to 

 anneal quenched steels over definite periods of 

 time at constant temperatures. Five steels were 

 determine the effect on electrical resistance of 

 used varying in carbon content from 0.08 to 0.45 

 per cent. The temperatures used were 125° C, 

 175° C. and 250° C. The total periods of an- 

 nealing varied from 90 to 190 hours. Results were 

 plotted as time against resistance. Micro-photo- 

 graphs were made of the specimens during the 



