Vol. XI. No. 2.57. 



THE AGRICULTURAL NEWS. 



71 



from the sample by means of a tine pair of forceps, and eacb 

 end is fixed to a square of the paper by means of a light, 

 wet brush, when on drying, the fibre may__ be straightened 

 by separating the squares of paper by means of forceps, and 

 its length measured. A variation of the method is to place 

 the fibre on a plate of black glass and to stretch it by draw- 

 ing a wet brush in a straight line over it. 



A further method of determining the average length of 

 the fibres in a small sample pulled from the seed consists in 

 placing them, carefully combed out, on a piece of thick, 

 uniform paper and drawing the outline of the space covered 

 by the straightened fibres; the area of this space depends on 

 the average length of the fibres, and it may bt measured b}' 

 cutting out the piece of paper marked by the outline, weigh- 

 ing it, and comparing its weight with that of a piece of the 

 paper of known area. The e.xtent to which this method may 

 be applied is limited; it is only suited for the comparison of 

 samples of the .same origin. 



MEASUREMENT OF AVERAGE DIA.METER, OR FINENESS. 



This requires a smaller number of observations than that 

 needed for estimating the average length. As in the case of 

 the latter quality, the diameter of different fibres varies; most 

 generally, the largest fibres are found on the seeds at the base 

 of the boll, much more rarely on those at the middle: while 

 the finest fibres are found on those at the apex; on the same 

 seed the fineness usually increases progressiiely from the base 

 to the apex. For comparing the fineness oi cottons of differ- 

 ent types, it is sufficient to make the measurements from sam- 

 ples taken from the middle of the seed; if, on the other hand, 

 it is required to ascertain the average fineness of a given 

 erop, the observations must be made on three seeds from each 

 capsule, the sanii>les being taken from the base, the middle 

 and the apex of each, and as they must be conducted on three 

 bolls at three different levels on each plant from three plants 

 representative of the crop, the total number of measurements 

 becomes at least 810. 



Experience has shown that the largest diameter of the 

 fibres is usually at the lower third; a further matter is that 

 direct measurement of the fibres spread out under the micro- 

 scope has been found more satisfactory than that of the 

 sections of the fibre cut and mounted in suitable media. 



MEASUKEMENT OF STKENi;T)i. Speaking exactly, the 

 strength or tenacity of a cotton fibre is measured by the 

 weight which, suspended at one end of it, is necessary to 

 cause it to break: the elasticity is measured by the e.xteiision 

 per unit of length which the fibre undergoes before being 

 broken. 



For measuring strength, Henri has invented an appa- 

 ratus consisting essentially of a marked Hoat having at its 

 upper end a metal stopper, provided with a pair of small 

 forceps; the jaws of the forceps are covered with sinall Mat 

 [)ieces of cork, in order to prevent the crushing of the fibre 

 which they hold. The float moves vertically in a calibrated 

 glass vessel, funnel shaped at the lower part, and provided 

 with a stop-cock similar to that of a burette. The upper 

 part of the apparatus comprises essentially a second pair of 

 forceps like the first, fixed to a copper rod in such a way as 

 to permit of rotation. This rod is held in a horizontal arm, 

 which may be moved up and down. A piece of blackened 

 wood is placed behind the upper pair of forceps in order to 

 facilitate observation on the fibre that is being examined. 

 For the purpose of determining the elongation of the fibre, 

 a needle pivoted to one of the uprights hnliling the apparatus 

 is fixed, by its shorter length on one .side ot the pivot, to the 

 lower pair of forceps. 



In conducting an observation, water is poured into the 

 vessel, the fibre is fixed in the forceps, ami the proper adjust- 



ments made. Water is then allowed to run slowly out of the 

 vessel, in order to cause the float to be partly supported by 

 the fibre, and when this breaks, the position of the mark on 

 the float relative to the graduations on the vessel, as well as 

 the position of the needle, are noted. After thi.s, bj- suitable 

 calculation, the breaking strain and the elasticity of the fibre 

 are ascertained. 



THE EFFECT OF SOLUBLE 



SALTS ON SOILS. 



The following is a summary, given at the end of 

 Bulletin No. 82 of the Bureau of Soils of the United 

 States Department of Agriculture, which deals with 

 investigations- of the effect of soluble salts on the 

 physical properties of soils : — 



From the foregoing experiments and discussion it is 

 evident that the causes producing a change of structure in 

 the soil are many and complex. 



It has been demonstrated, furthermore, that the addi- 

 tion of small amounts of soluble salts affects the physical 

 properties, and therefore the structure of the soil. 



Some results obtained are not explained by hitherto 

 known facts and are apparently not in accord with theories 

 regarding the action of salt solutions on solid particles. 



From the results no predictions can be made regarding 

 the specific direction or the amount of the action of .salts on 

 particular soils, but it can be as.serted positively that there 

 is a measurable change in the structure of a soil due to the 

 addition of soluble salts. It is conceivablo that there are 

 causes producing changes other than those which are gener- 

 ally considered. 



The effect of salts is more pronounced in a soil contain- 

 ing a large percentage of fine soil particles, and this leads to 

 the conclusion that colloid-like clay particles are affected 

 most by soluble salts, and in turn affect most the structure of 

 the soil. 



The actual nature of the condition produced in the 

 smallest soil particles is not known beyond the fact that 

 flocculation and deflocculation may be produced. 



The photographs of soil layers, in addition to these 

 effects, show an apparent difference in the grouping of the 

 smaller aggregates with reference to the larger soil grains. 



The fact that the problems are complex does not detract 

 from the i)raccical conclusion that soluble salts, whether they 

 supply to a soil elements necessary for plant growth or not, 

 m.iy produce in the soil measurable changes in structure 

 which in turn greatly influence plant growth. 



Silk Production in Italy.— The Italian cocoon 

 crop of 1910 amounted to 22,658,0005)., as compared with 

 21,870,000 ft. in 1909 and 27,933,000 lb. in 1908, The crop of 

 Piedmont in 1910 was a little ox-er 10 million ft., as 

 against 9 million in 1909, and 1.5 million in 1908. Tn 

 1910, as in 1909, Piedmont, instead of producing, as usuul, 

 more than one-half of the total Italian crop, produced .so 

 small a quantity as greatly to diminish the total crop uf 

 Italy. The failure of the Piedmontese crop was due in part 

 to the cold and rainy weather of the spring months which 

 affected the growth of mulberry leaves, and in part to 

 Bii'spis 2)eiitiiiji>iia, which made its appearance early in the 

 spring and caused considerable damage. The quality of the 

 crop was, however, satisfactorj', and was richer in silk than 

 the crop of 1909. (From the Jovrnrd of the Raval Society 

 of Arts, January 20. 1912, p 292.) 



