DR. DAUBENY ON THE ROTATION OF CROPS, ETC. 

 100 grains of real ash contain, — 



221 



These results are interesting on two accounts ; first, as they show what the com- 

 position of barley is when cultivated under natural circumstances, or within what 

 limits its variation from a normal condition may be circumscribed ; secondly, as 

 they confirm tlie general exactness of the preceding analyses, by the correspondence 

 which is seen to exist between the composition of the shifting crop, as ascertained 

 by experiment, and that of the sample obtained from Mr. Druce's brought out by 

 the above method of computation. 



As the analyses of the ash, both in the case of the straw and of the grain, were 

 performed by Mr. Way, whilst the proportion between the grain and straw, as well 

 as that subsisting in each instance between the crop and its ash, was ascertained by 

 myself, the statement which I have just submitted as to the real composition of the 

 crop, calculated from these data, would hardly have presented so near an accordance 

 with the analysis made of the entire crop which I had obtained in the Botanic Garden, 

 had not both the one and the other been executed with considerable care. 



It was far otherwise, however, when we compared our results with those of Sprengel, 

 in which, amongst other striking discrepancies, we observe, that the proportion of 

 soda stated to exist in the grain exceeds that of the potass, whilst in our analyses, 

 only so much as was equivalent to the amount of chlorine appeared to be present*. 



* Our analysis, of Hordeum vulgare. 



Sprengel's, of Hordeum distichum. 



Bichon's, as quoted by Will. 



Silica 33-2 



Phosphoric acid 31-2 



Sulphuric acid 3-4 



Carbonic acid 0-0 



Chloride of sodium 2*3 



Potass 19-1 



Soda 0-0 



Magnesia 7*6 



Lime 3-6 



Alumina 0-0 



100-4 



Silica 50-2 



Phosphoric acid 8-4 



Sulphuric acid ........ 2-5 



Carbonic acid 0-0 



Chloride of sodium 0-0 



Potass 11-80 



Soda 12-30 



Magnesia 7-65 



Lime 4-50 



Alumina 1 -50 



99-95 

 2 G 2 



Silica 21-99 



Phosphoric acid 40*63 



Sulphuric acid 0*26 



Carbonic acid 0-00 



Chloride of sodium .... O'O* 



Potass 3-91 



Soda 16-79 



Magnesia 16*05 



Lime 3-.36 



Alumina 0-00 



97-03 



