30 THE CONNECTICUT AGRICULTURAL 



ued for some time, as is shown by the higher percentage of solu- 

 ble phosphoric acid in the material after lying for a week. As 

 far as concerns its mechanical condition the superpliosphate pre- 

 pared as above was inferior to the best " acid phosphates " in our 

 market. It was somewhat lumpy and could not be conveniently 

 drilled without sifting. The lumps were very soft, however, and 

 easily pulverized. Constant stirring with a hoe while the mixture 

 is cooling does much to prevent the forming of lumps. In this 

 case tlie operation was decidedly economical, for by it soluble 

 phosphoric acid was got for about $S.OO per 100 lbs., while in 

 market it was selling for from $10 to $12, and its fertilizing- 

 effect was satisfactory. Generally speaking the I'armer can buy 

 acid phosphate cheaper than he can make it. Home manufacture 

 is only advisable when farm work is slack and the raw phosphate 

 can be got at a very low price. 



Ground bone is used considerably in case-hardening small arti- 

 cles of iron, and where the consumption is not large, manufactur- 

 ers throw away the spent char, or will sell it at a low price. 

 Such material it may be vei-y profitable to utilize for superphos- 

 phate manufacture on the farm. 



916 is made from the Navassa rock which contains miicii iron 

 and alumina. A larger share of the phosphoric acid may have 

 been soluble in water when the goods were first manufactured, 

 but if so, a portion has reverted, or been made again insoluble in 

 water-. This effect is with great probability attributed to the 

 iron and alumina present. 



987 contains more than double the amount of soluble phospho- 

 ric acid usually found in high grade superphosphates and at 170 

 per ton retail we believe is the cheapest source of soluble phos- 

 phoric acid in our market. 1036 is an article of still higher grade 

 than the last mentioned, but is not in the retail trade. 987 is 

 manufactured in this country, 1036 is imported from England. 



l^ITROGE]!fOUS (AmMONIATEd) SUPERPHOSPHATES AND GuANOS. 



Here are included all those superphosphates which contain ni- 

 trogen in any form — excepting the formulas or " special manures,'\ 

 to be noticed in the next section — as well as guanos, either in 

 their natural state or manipulated. The articles of this class with 

 few exceptions also contain more or less potash and such are 

 known as "complete manures." 



