78 



EXPERIMENTS UPON POTATOES, 



[AppeTidiXf 



The gypsum used turned out to be genuine on analysis.* 



REMARKS UPON THE PRECEDING EXPERIMENTS. 

 1°. Effect of the drought. — It is to be observed, in the first place, that the 

 great drought of the season exercised an unfavourable influence upon the re- 

 sults of these experiments also. It is necessary, therefore, to suspend our judg- 

 ment in some measure regarding them — until future experiments in other sea- 

 sons shall confirm or modify them. 



2°. Inferences to be drawn frovi the colour of the crop. — A new feature in- 

 troduced by Mr. Wilson in the account of these experiments, is the appearance 

 presented by the several crops at different specified periods after the dressings 

 were applied. 



It is a common thing for practical men to estimate the relative produce of 

 different fields or parts of the same field by their appearance, and especially by 

 the colour of the growing crops. Yet that this is not to be depended upon in 

 a corn crop, is proved by the observation that up to the end of June appearances 

 in the oat field were most in favour of the nitrate of soda, the guano being se- 

 cond, and the soot third in order. Yet, when reaped, the — 



Nitrate gave an increase of only 2 J bushels per acre. 



Guano 24 lbs. per acre. 



Soot 6 bushels per acre. 



The nitrate did give a little more straw than either of the other two, but that 

 the colour is not an unfailing criterion even as to the produce of straw or of 

 nay is shewn by the experiments upon oats and upon hay. In both of these 



' List of prices paid for the manures used in the foregoing experiments: — 



1. Foreign Guano 25s. per cwt. 



2. TurnbuU's Guano 8s. " 



3. TurnbuU's Improved Bones 6s. " 



4. TurnbuU's Humus Is. per bushel 



5. Nitrate of Soda .... 25s. per cwt. 



6. Sulphate of Soda (dry) 6s. " 



7. Sulphate of Ammonia 20s. " 



8. Soot 3id. per bushel. 



Nos. 2, 3, 4, and 7, were manufactured and furnished by TurnbuU and Company, Chem- 

 ists, Glasgow. The British (Guano No. 2) is said to be made up as follows :— 



2 cwt. of Sulphate of Soda. 

 2 cwt. of Sulphate of Ammonia. 

 1 cwt. of Common Carbonate of Soda. 

 15 cwt. of Improved Bones, manufactured by TurnbuU «fc Co. 



20 cwt., or 1 ton. 



The Improved Bones are said to be halT dissolved bones and half wood-charcoal. I be- 

 lieve the bones include animal matter, as \ am informed the carcases of old horses, Ac, 

 are aU used in the manufacture. James Wilson. 



Freeland, Erskine, 20th February, 1843 



