536 



Agricultural Chemistry — Turnips. 



substances of the specimen, the latter having been consumed and 

 vaporized by the burning process. The knowledge which these 

 simple experiments may afford is never to be overlooked in con- 

 sidering the composition of an agricultural product, and estimating 

 its probable value, or the economy of the manuring, or other 

 means which have been employed in its growth. A judgment 

 formed thus alone, however, of the comparative characters of 

 different specimens would be fallacious, owing chiefly to the facts 

 that the dry matter of different specimens of the same kind of 

 plant may differ much in composition, and that a very large pro- 

 portion of our agricultural produce is not allowed to ripen its seed 

 and attain a somewhat fixed condition of dryness not materially 

 affected by collection, storing, and transmission, but is taken whilst 

 the vital circulation of the plant is still proceeding with consider- 

 able vigour, causing, long after removal from the land, a rapid 

 exhalation of watery vapour, tending very much to mislead as to 

 the amount of dry matter really contained in the substance under 

 examination. Unless, then, a series of such specimens — the com- 

 parative characters of which are to be estimated — be treated in 

 every respect similarly, as to time of gathering, weighing, &c., 

 serious errors must occur. 



When ultimate ripened products are the subjects of examina- 

 tion, there is little difficulty in conductino; a series of drying ex- 

 periments, so that the resuhs shall be true indications of the 

 differences really dependant on climate and culture ; and although 

 in such cases the range of variation in the amount of dry matter 

 is small, yet the variations themselves are very significant, bespeak- 

 ing at once the conditions of growth, and, within certain limits, 

 the probable qualities of the products. 



There can be little doubt that, after reliable standards have 

 been fixed, a knowledge of the true undoubted per centage of dry 

 matter in specimens of green produce also might materially aid 

 our judgment of their other characters, but, as yet, neither have 

 we these standards, nor are the methods of different experimenters 

 so uniform that their results can compare one with another. So 

 litde, indeed, is really fixed and generally admitted regarding 

 both the methods of and the proper inferences from such experi- 

 ments, that the results of the same operator will, in his own view, 

 be the more doubted the more he learns of the lesson they are 

 calculated to teach; and before there can be any common argu- 

 ment or comparison conducted on such subjects, there must be 

 some uniformity of method agreed upon. In illustration of this 

 necessity one or two experiments only are needed. 



A quantity of turnip-leaves were taken direct from the field to 

 a barn about sunset, and were immediately weighed into lots of 

 25 and 50 oz. each. These bundles were laid upon straw, and 



