538 Agricultural Chemistry — Turnips. 



wiping, but an extended series of determinations cannot be con- 

 ducted under equal circumstances and with the necessary despatch 

 without washing-, by which soluble substances may to some extent 

 be removed, or an absorption of water may take place. With 

 the view of ascertaining the degree of error to which the washing 

 of bulbs for drying and burning may lead, six lots^ consisting 

 each of five turnips, were taken, and the leaves were cut off, 

 leaving a sufficient handle ; three of the lots were carefully cleaned 

 without the use of water, the other three being scrubbed with 

 a brush in water, in which they were allowed to remain for ten 

 minutes or a quarter of an hour ; they were then taken out, rubbed 

 dry with a cloth, sliced, and weighed. After exposure to a tem- 

 perature of 212° for a sufficient time, the per centages of dry 

 matter were as under : — 



Lot. 



Without 

 washing. 



With 

 washing. 





. . 8-36 



7-96 



2 



. . 8-03 



7-79 



3 



. . 7-64 



7-30 





Average 8*01 



7-68 



There was evidently some difference in the specimens them- 

 selves, but the washing process gives in the main a less per 

 centage of dry matter than the other. Without washing there 

 must always be expected a small excess, and with it a slight de- 

 ficiency. In the particular instances quoted the deficiency was 

 likely to be greater than in the usual conduct of the process, as 

 the operation was purposely rather prolonged, that the extreme 

 effects might be ascertained. It is admitted, however, that wash- 

 ing is an objectionable procedure ; but when drying and burning 

 experiments are conducted on an extended scale, the results will 

 be more uniform in character and more comparable one with 

 another than were any other method adopted, as all such either 

 take up so much time that the specimens must, with the risk of 

 change of weather, be collected at different times, or so many 

 persons must be employed that the desirable surveillance is im- 

 practicable. 



Having given thus far some general statement as to the manner 

 in which our drying results have been obtained, those of our 

 readers who understand such matters will be able to decide for 

 what purposes our figures may be relied upon, and wherein they 

 are likely to be wide of the exact truth. For ourselves, we are of 

 opinion that, taken in series rather than individually, they may be 

 trusted in discussing any points with which our general knowledge 



