AGKICULTUEAL CHEMISTRY AGEOTECHNY. Gil 



liiinule, a strip of moistened load acetate paper is placed over the moutli of the 

 tlask and the boiling continued two minutes more, when the paper is removed. 

 If the soil is acid the paper will be darkened on the underside in proportion to 

 the degree of acidity. If it is nonacid, no darkening will occur if the test has 

 been performed as just outlined." 



Calcium c-hlorid. which is added for the purpose of making the test much more 

 scnsilive, reacts with the comparatively insoluble soil acids and forms a small 

 amount of hydrochloric acid wliich readily lil)erates the hydrogen sulphid from 

 the zinc sulphid. The test is said to detect much smaller amounts of soil acids 

 than the litmus paper test. " The test has been applied to a considerable num- 

 ber of soils and also other materials of known reaction and as yet not a single 

 objection to the test has arisen. As a quantitative method, an effort is being 

 made to measure tlie degree of acidity by titrating with standard iodin solution 

 the hydrogen sulphid which a soil will liberate. Whether this will worii with 

 all soils has as yet not been determined. • By using this test for the end point in 

 the A'eitch lime water method for acidity or lime requirements, the present 

 Veitch method is considerably shortened and made far more accurate." 



Inasmuch as the test can be made approximately quantitative and still require 

 only vei-y simple apparatus and very little time (10 to 15 minutes), it makes a 

 valuable field procedure. "The principle of this quantitative method, depends 

 upon the fact that for any particular class of soils the degree of acidity is 

 closely proportional to the intensity of color produced on the paper when the 

 test is conducted as previously outlined. The color on the test paper needs only 

 to be compared to a standard color scale and from an accompanying table the 

 degree of acidity or lime requirements is read off directly. This standard color 

 scale is now being prepared and checked up with standard, soil acids made by 

 new methods."' 



A shaker for the mechajiical analysis of soil, F. Ward (Jour, Indus, and 

 Engin. Chcm., G (1914), No. 2, pp. llfl, lJi8, fig. 1). — ^A description of a homemade 

 device. 



" The writer believes that hi.s method is better than the one used by the 

 Bureau of Soils in tv\'o respects. In the first place the machine is simple. and 

 inexpensive. A greater advantage is the saving of time. Clean separations can 

 be effected in three hours, and in some cases two hours; this is a saving of at 

 least four hours over the Bureau method. If the quantity of the water used in 

 the bottles is reduced one-half, a clean separation results in much less than 

 three hours, but there is a tendency for the grains to suffer some abrasion." 



A shaker for the mechanical analysis of soils, C. C. Fletcher {Jour. Indus, 

 and Engin. Chcm., 6 {WL',), No. 6, pp. 517, .178).— It is pointed out that although 

 the machine mentioned in the abstract above is simple and inexpensive it carries 

 only IG bottles while that of the Bureau of Soils holds 4S. It must also be 

 run at a fixed si^eed to be efficient. The length of time required by the Bu- 

 reau of Soils apparatus is not so great as stated, since a majority of soils, 

 especially sandy soils, do not need seven, hours' shaking. " The length of time 

 of shaking does not result in any loss of time to the operator, as the analyst 

 merely keeps 48 soils shaking on the machine all the time and can not com- 

 plete the analyses rapidly enough with a force of three men to keep the machine 

 cleared of samples ready for analysis. If more samples should be required, all 

 that is necessary is to run the machine during the night, and thus the capacity 

 of the machine would be doubled." 



New investigations on the determination of citric acid-soluble phosphoric 

 acid in Thomas slag powder, M. Popp (Chcm. Ztg., 37 (1913), No. 109, pp. 

 1085-1087, fig. 1).—In this article the Popp method (B. S. R., 30, p. 809) is 



