1920] An Interesting Fertilizer Problem 95 



Knowing- that one per cent of chlorine could not kill tobacco, boxes 

 were prepared in which we used as much as 200 lbs. of sodium chloride 

 per acre. As was expected this did not injure the plants. The chlo- 

 rides do not affect the growth, but only the burning' quality of the 

 tobacco. 



We next tried the fertilizer on tomato plants and found that these 

 were injured, but not as much as the tobacco plants. Then we investi- 

 gated various solutions of the fertilizer. We found it was the water 

 solution alone that injured the tobacco. A small plant in a beaker was 

 killed in twenty-four hours by the application of a solution that repre- 

 sented 2,000 lbs. per acre. Next we removed the organic matter by 

 prolonged heating, taking up the ash with hydrochloric, sulphuric 

 and nitric acids. The plants were injured not at all by the M^ater 

 solution of these salts, but little growth was shown, because the organic 

 matter unquestionably stimulates plant growth, as could be shown in 

 the study of stable manures. It was noted with interest that the nitric 

 acid solution gave after a time a most vigorous growth. This might 

 have been expected. We then tried water solution of the fertilizer 

 under investigation after heating for an hour at 120° for thirty min- 

 utes. We found that this solution when applied in quantities repre- 

 senting 1,000 lbs. per acre gave excellent results. 



The toxic substance or substances present seemed to be removed 

 or changed by heat. We repeatedly demonstrated the good results 

 with the fertilizer thus treated. We now had the explanation of the 

 puzzling fact about the chlorine.. In removing the chlorides with silver 

 sulphate, heat was employed to avoid the loss of the phosphates. The 

 heat had destroyed the toxic substances in this case as in the case 

 of the straight samples. 



B.y accident we discovered that the toxic substances are also re- 

 moved by leaving the fertilizer exposed to the sunlight in a warm 

 place, as a bottle containing the fertilizer was left for one week in 

 the balance room where it was exposed to strong light from the south. 

 Water solution of this exposed fertilizer had no effect whatsoever on 

 tobacco plants. 



Thus it appears that there is an organic substance present in this 

 fertilizer, which is toxic to tobacco plants and tomato plants, while it 

 has no effect upon rye and clover. This toxic substance is made harm- 

 less by heating or by exposure to sunlight. What the substance is still 

 remains a puzzle. Thinking it might be a nitrogen compound, prob- 



