460 ANNUAL REPORT OF THE Off. Doc. 



double that price. In other words, for the 250 pounds of phosphorus 

 in the acid phosphorus you pay |82 instead of |8 in the raw rock, 

 which has the ek^ment we want. Let us go a step further; he will 

 take two tons at .|32 and mix them with a little nitrate of potash, of 

 which we have enough for 1,700 years in the soil, and he uses that 

 and a good deal of filler to make four tons, and he gives it a name 

 like the ''White Ox," or the "White Elephant," and puts it on the 

 market. One sample we analyzed last year we found to contain 2 

 per cent, ammonia, 8 per cent, phosphoric acid, 2 per cent, potassium, 

 1 2-3 per cent, nitrogen and 3^ per cent, phosphorus element. They 

 sold it at |20 per ton and it does not contain one-quarter as much 

 phosphorus as you buy in the raw rock for $8. We will carry this 

 point a little further: you have four tons of acid phosphorus made 

 out of one ton of complete phosphorus. Now, what do you pay 

 for acid phosphorus? 



A Member: Thirty dollars. 



A Member: Twenty-five dollars. 



PKOF. HOPKINS: Probably an average of $20; well, you have 

 four tons of acid phosphorus at |20, which contains as much phos- 

 phorus as the same amount of raw rock would at |8. 



A Member: Eight dollars and seventy-five cents here. 



PROF. HOPKINS: Well, |8.75 then. Of course you have some 

 nitrogen and ammonia, if you want them. 



QUESTION: If your land was short in potassium, and had all 

 the phosphorus it needed, what then? 



PROF. HOPKINS: Well, as I said a little while ago, the far- 

 mers are using now, annually, more than |20,000 worth of acid salts. 

 I would probably call it potassium chlorate, but you know it as po- 

 tassium salts. You can get it cheaper in that form than in any 

 other. We can buy it at |4o delivered, or you can get cement at |15. 



A Member: Forty-three dollars here. 



PROF. HOPKINS: Very frequently members buy cement and 

 get as much potash as if they buy the potash they pay |64 for. 

 Why should you pay for the shifting and handling of four tons ol 

 material on the land when you can get it in one ton? 



QUESTION: Do you think we make a mistake in mixing potas- 

 sium chlorate and muriatic potash in 14 per cent, acid phosphate? 



PROF. HOPKINS: That is a very good idea, but I think it comes 

 a little high when you can get the raw rock phosphate so much 

 cheaper. 



MR. SCHWARZ: If your figures are right you should do better to 

 get the pure bone. 



PROF. HOPKINS: Well, the bone has just the same relation to 

 phosphorus as acid phosphorus. If your land is deficient and you 

 cannot get phosphorus, you can use bone. Bone is even preferable 

 to acid phosphorus, but it is better still to use the rock phos- 

 phorus. You can buy three times as much rock phosphorus for the 

 money. 



