490 EXPERIMENT STATION KECOED. 



all of the land available has been taken np, about 35,000 or 40,000 acres being 

 now under cultivation. 



Farming with explosives, S. J. Crawford (Bicn. Rpt. Kans. Bd. Agr., 11 

 (1909-JO), pp. //5-//S). — This is a discussion of the economy of breaking farm 

 land with explosives. 



It is shown that at a cost of about $1.50 per acre an 8-acre field was dyna- 

 mited by placing the dynamite in the ground from 2 to 6 ft. deep and at dis- 

 tances of from 20 to 30 ft. " When the fall and spring rains came the water, 

 which formerly stood for days on the gi-ound. was immediately absorbed, leav- 

 ing the field dry and apparently in good condition." " The yield per acre has 

 shown a marked increase." 



The mechanical culture of the soil, M. Ringelmann (Rev. Sci.. [Paris], 49 

 (Wll), I, No. 11, pp. 336-339) .—This article deals briefly with the applications 

 of various kinds of mechanical power to farm work. 



Working trials with hay-harvesting machinery, C. V. Birk and M. Daix 

 (TuJsfikr. Landokonomi, 19 tl, No. 6, pp. 377-.'i00, figs. 11). — This report gives 

 the results of trials of 9 different rakes, mostly side-delivery rakes, and de- 

 scribes each. 



[The cost and net returns of agricultural work] (Jour. Sac. Agr. Brabant 

 et Hainaut, 55 (1910), No. 52. p. 1272; 56 (1911). No. 1, pp. 5, 6).— The article 

 discusses the relative economy of having work done by a labor-saving machine 

 and by hand labor, as illustrated by machinery for cutting hay, harvesting, and 

 other agricultural machinery. 



Practical silo constrviction, A. A. Houghton (Nerv York, 1911, pp. 69, figs. 

 18). — A treatise on simple and practical methods of constructing concrete 

 silos of all types, with impatented forms and molds. 



The kind of wood for a silo, E. A. Burnett (Breeder's Gaz., 59 (1911), No. 

 16, p. 1002). — A discussion of the durability of different kinds of wood com- 

 monly used for building silos. 



The new cement manure shed at Flahult, H. von Feilitzen (Svenska Moss- 

 kulturfdr. Tidskr., 25 (1911), No. 2, pp. 135-Ul, figs. 2).— A description of the 

 manure shed with illustrations is given. The area of the shed is 11 by 11 

 meters (about 43.3 ft. square), or 4 square meters per animal for a herd of 30 

 cows. 



The destruction of hydraulic cements by the action of alkali salts, E. 

 Burke and R. M. Pinckney (Montana Sta. Bui. 81, pp. ',7-131, figs. i6).— This 

 bulletin, continuing work previously reported (E. S. R., 20, p. 288), deals in 

 definite order with the chemical changes which bring about the disintegration 

 of cement. In the work Portland, slag, and natural cements were used, being 

 tested in regard to their resistance to sea water and various salts, including 

 sodium sulphate, magnesium sulphate, sodium carbonate, sodium chlorid, cal- 

 cium hydrate, and calcium sulphate, in solutions of various concentrations. 



The authors point out that the disintegration of cement by alkali salts is 

 chiefly due to the reaction of these salts with the calcium hydroxid of the 

 cement. As a result of these reactions, relatively insoluble new compounds 

 having greater weight and bulk than calcium hydroxid are formed, and force 

 apart the particles of cement and thus weaken or break the binding material. 

 The binding material is in some instances leached out. As a result of these 

 interactions with calcium hydroxid, sodium sulphate when present produces 

 sodium hydroxid and gypsum, magnesium sulphate produces magnesium hy- 

 droxid and gypsum, and sodium carbonate produces sodium hydroxid and cal- 

 cium carbonate. In the last-named instance, however, there is little increase 

 in bulk, but instead the silicates and aluminates are attacked and dissolved. 



