33 



H. Lough bridge,* to exert the maximum effect after a water-bath di- 

 gestioD of five days. 



In determining the different soil constituents especial care must be 

 taken to subject them in the various operations to as nearly similar 

 conditions as possible, as the principal object is to obtain comparative 

 results ; to this end the several soils are air- dried together, digested for 

 an equal time at nearly the same temperature in acids of uniform 

 strength, &c. 



Owing, however, to the large amount of time demanded by such work, 

 the process of digestion in water containing carbonic acid was not em- 

 ployed, neither was any attempt made at a mechanical analysis of the 

 soils received. 



COLLECTING THE SAMPLE. 



The collection of samples of soil is a delicate and important operation, 

 as it is on the average sample that the physical and chemical properties 

 of the soil are determined. They should represent, as far as possible, 

 the average of the bad and good qualities of the soil. 



Select, in the field, four or five places, at least, per acre, taking care 

 that these places have an homogeneous aspect, and represent as far as 

 possible the general character of the whole ground. If the field, how- 

 ever, presents notable differences, either in regard to its aspect or its 

 fertility, the sample gathered from the different parts must be kept 

 separate. 



The sampling of the arable soil should be made only after the raising 

 of the crop and before it has received any new manure, in the following 

 manner:! 



Have a wooden box made, 6 inches long and wide, and from 9 to 12 inches deep, 

 according to the depth of soil and subsoil in the field. At one of the selected places 

 mark out a space of 12 inches square; dig around it in a slanting direction a trench, 

 so as to leave undisturbed a block of soil, with its subsoil, from 9 to 12 inches deep ; 

 trim this block to make it fit into the wooden box, invert the open box over it, press 

 down firmly, then pass a spade under the box and lift it up and gently turn over the 

 box. 



In the case of very light, sandy, and porous soils, the wooden box may be at once 

 inverted over the soil and forced down by pressure, and then dug out. 



Proceed in the same way for collecting the samples from all the 

 selected places in the field, taking care that the subsoil is not mixed 

 with the surface soil. The former should be sampled separately. 



In preparing the plot for the gathering of the sample, take care to 

 have it lightly scraped so as to remove any deijris which may be acci- 

 dentally found there. 



The sample should be taken only from spots that have not been culti- 

 vated, where " virgin soils" are concerned, and as a rule not from ground 

 frequently trodden on, footpaths, roads, &c., nor from squirrel holes, 



* Arner. Jour, of Science, vol. vii, p. 20. 



tFrom the instructions for selecting samples, issued by the Royal Agricultural So- 

 ciety of England. 



13735 Xo. 10 3 



