CHEMICAL SCIENCE. 285 



SOIL ANALYSIS. 



A recent writer in the North British Agriculturist makes the following 

 remarks on the subject of soil analysis : 



" To analyze a soil, and determine from the results the degree of its fer- 

 tility and its adaptation to particular crops, was one of the problems placed 

 before the agricultural chemist, and from its solution the greatest advanta- 

 ges to agriculture were anticipated. As yet these expectations have not been real- 

 ized, nor can this be considered as a matter of surprise. The progress of our 

 knowledge, in place of simplifying, has complicated the question, and has 

 shown that the fertility and infertility of a soil is dependent upon a variety of 

 circumstances, of which its chemical composition is only one. Instances exist 

 in which the barrenness of a soil can be distinctly traced to the deficiency of 

 some one or other of the necessary elements of plant-life ; but in other cases, 

 a barren and a fertile soil may present an almost perfect similarity in 

 composition, and contain all the elements required by plants in proportions 

 known to be amply sufficient for their healthy growth. The difficulty of 

 explaining these facts has been increased, just in proportion as soil analyses 

 have become more minute ; for their tendency has been to show that the 

 instances in which infertility is due to the absence of any of the essential 

 constituents of the plants are comparatively rare, and that quantities which 

 we are apt to overlook as totally unimportant, may be amply sufficient for 

 all that is required. One-tenth of a per cent, of potash, soda, or phosphoric 

 acid, may appear a quantity so small that the chemist might be justified in 

 neglecting it, and yet a soil containing these quantities is capable of afford- 

 ing an abundant supply of these elements to many generations of plants ; and, 

 notwithstanding this, there are soils containing a much larger quantity of 

 these substances, which, if not absolutely barren, are only capable of sup- 

 porting a very scanty vegetation. These facts have rendered it obvious 

 that it is not merely the presence, but the accessibility, so to speak, of the 

 constituents of a soil that must be determined; and when the chemist, in 

 addition to the exact proportion of these minute quantities, is required to 

 ascertain the various forms of combination in which they exist, it is natural 

 that he should show little disposition to enter upon a branch of investigation 

 of such complexity, and which, in the present state of our knowledge, is 

 likely to give only negative results. 



" The difficulties of this investigation have been so fully recognized by 

 Liebig, that he has pronounced it impossible to arrive at a satisfactory knowl- 

 edge of the composition of the soil, and its suitableness for particular crops, 

 by analysis alone." 



ON THE ANNUAL YIELD OF NITROGEN PER ACRE IN DIFFERENT 



CROPS. 



The following is an abstract of a paper on the above subject, presented 

 to the British Association, 1858, by Messrs. Lawes & Gilbert: 



The authors stated, in commencement, that they had, at a former meeting 

 of the Association, announced, that the amount of nitrogen yielded per acre 

 per annum, in different crops, even when unmanured, was considerably 

 beyond that annually coming down, in the form of ammonia and nitric acid, 

 in the yet measured and analyzed aqueous deposits from the atmosphere. 

 The investigations upon this subject were still in progress; and a desirable 



