116 EXPERIMENTS ON CABBAGE AND ROOT CROPS. 



f Cabbage, parsnips, and probably beet, mangel -wurtzel, 

 and onions, appear to contain a more than usual amount of 

 sulphur. Have these sulphates, therefore, or either of them, 

 any special action upon such crops ? 



g The hop delights in woollen rags, in which sulphur is a 

 comparatively large constituent, (5 per cent ;) will this plant be 

 grateful for an application of sulphates, either alone or mixed 

 with the other manure applied to it ? 



h Is the quality of a crop its flavour, its nutritive proper- 

 ties, or its chemical composition affected by the application of 

 these salts ? 



The field of experiment here indicated is sufficiently wide, 

 and no good experiments on any of these topics will be without 

 their use. The experimenter, however, must bear in mind, 

 that in many cases he will be unable to judge of the actual 

 effect of these sulphates till the crop is reaped or gathered, and 

 weighed. The sulphate of soda does not darken, but rather 

 pales the green colour of the plants treated with it, and often 

 diminishes their succulence instead of increasing it, as the salts 

 of ammonia and the nitrates do. 



Finally, in comparative experiments with the two sulphates, 

 it is of importance to apply them in proportions which shall 

 contain the same quantity of sulphuric acid, for only then can 

 their effects be strictly comparative. The chemical reader will 

 at once understand the reason of this. To the unscientific 

 reader it may be sufficient to state in addition to what he will 

 find in the preceding chapter, 8 that equal chemical effects 

 are not produced by equal weights of the potash and soda which 

 these two sulphates contain, but by the quantities which are 

 combined or contained in the salts along with equal weights of 

 acid. 



Hence, if we apply a quantity of each which contains, say 

 50 Ib. of acid, not only will the amount of chemical effect which 

 the acid may produce be the same in both, but the potash in 

 the one will be able to produce the same amount of chemical 

 effect as the soda in the other. And thus, whether we ascribe 

 the effects they may appear to have upon the soil or plant to 

 the acid or to the alkali they contain, the effects of the two 



