Experiments upon Swedes. 159 



when such experimental plots are omitted in a series of field 

 experiments. 



My twelve experimental plots were treated in regard to 

 manure as follows : — 



At the rate of 

 per Acre. 



To Plot I. was applied well roi^eTO/arm^arfZ Twarmre 15 tons. 



„ 11. „ „ cpjpsum 6 cwt. 



„ III. ,, ,, bone-ash dissolved in sulphuric acid . . .. 6 cwt. 



,, IV. „ „ sulphate of ammonia 6 cwt. 



^ (■ bone-ash dissolved in sulphuric acid, 6 cwt. 



" ■ " " \ sulphate of ammonia 6 cwt. 



together 12 cwt. 



„ VI. „ „ bone-ash, dissolved in sulphuric acid . . .. 12 cwt. 



„ VII. ,, ,, sulphate of potash 6 cwt. 



„VIII. „ „ Nothing. 



,, IX. „ „ crystalUsed sulphate of soda 12 cwt. 



i bone-ash, dissolved in acid .. .. H cwt. 

 sulphate of potash 6 cwt. 

 sulphate of ammonia 6 cwt. 



together 18 cwt. 



„ XI. „ ,, bone-ash dissolved in sulphuric acid . . .. 3 cwt. 

 ,, XII. „ „ Nothing. 



These manuring- matters were all finely powdered and thoroughly 

 mixed with ashes, in order to secure their more uniform distri- 

 bution over the land. 



When bone-ash is dissolved in sulphuric acid, soluble phos- 

 phate and gypsum are produced. Soluble phosphate alone 

 cannot readily be used in field trials. The influence of the 

 gypsum in the dissolved bone-ash upon the produce in these ex- 

 periments, however, is determined by the dressing of gypsum 

 applied to Plot No. II. At the same time we have here sul- 

 phuric acid in combination with ammonia, as Avell as with soda 

 and with potash, and thus the means of comparing the manurial 

 efficacy of sulphuric acid with that of phosphoric acid. To 

 apply sulphuric acid diluted with water would have been to no 

 purpose ; for since the soil contained rather more than 12 per 

 cent, of carbonate of lime, gypsum would have been formed imme- 

 diately on putting free sulphuric acid on the land. Since turnips 

 contain a good deal of sulphur, it is not unlikely that sulphates 

 will be beneficial to that crop, at least on soils naturally deficient 

 in sulphate of lime, the usual state in which sulphuric acid 

 occurs in soils. In these experiments we have sulphuric acid in 

 combination with lime as a difficult soluble salt with an earthy 

 base, and sulphuric acid in combination with the three alkalies — 

 potash, soda, and ammonia. With the three last-mentioned 

 substances sulphuric acid forms salts more or less readily soluble 

 in water. It might therefore have been expected that sulphuric 

 acid, if at all capable of showing any specific effect on turnips, 



