1()<S 



HATCH EXPERIMENT STATION 



[Jan. 



in our general markets. In this article we pointed out the 

 special modes of analysis that were in use in testing this 

 material, also certain changes that have taken place in many 

 localities in preparing the phosphatic slag by the addition 

 of silica in a fusing process to change the free lime which is 

 present in the slag to a silicate of lime, thus showing, it is 

 claimed, a larger percentage of available phosphoric acid. 



Samples of phos})hatic slag have been collected in our 

 general markets during the past year. This would indicate 

 that this class of material was claiming the attention of agri- 

 culturists more than in the past. The extensive introduction 

 of new methods of iron manufacture has largely increased 

 the supply of phosphatic slag. Results of field experunents 

 have shown the superior value of this material and demon- 

 strated its fitness as a manurial matter. In view of the 

 above facts, we have again taken this subject up for dis- 

 cussion. 



The following table gives the results of analysis of samples 

 of phosphatic slag made at the laboratory during 1004, in 

 comparison with the average of anal3'ses of slags made at 

 the station in years past. Sam})le I. Avas imported from 

 England in 1904; Sample II. was collected in our general 

 markets during the spring of 1004 ; Sample HI. was the 

 average of all previous analyses made at the station. 



Analysis of Samples (Per Ce)it.). 



Siiuiple I. 



Sample II. 



Sample III. 



Moisture 



Total phosphoric acid, 

 Available phosphoric, a<'i(l, 

 Insoluble phosphoric acid, 

 Calcium oxide, 

 Insoluble matter, . 



.15 

 18.61 



50.58 



none 

 •20.52 

 4.96 

 15.. 56 



46.78 

 18.78 



.09 

 20.61 



4.05 

 19.02 

 50.32 



6.59 



From the results of the above compilation of anah'ses it 

 will be seen that the present phosphatic slag does not differ 

 materially from that of the past. The two samples analyzed, 

 during the year showed the presence of free lime, which fact 

 was recognized and the mode of analysis was so modified as to 



