4 BULLETIN 798. U. S. DEPARTMENT OF AGRICULTURE. 
paid and which must be ground and bagged and transported, is one 
of the fundamentals in the fertilizer industry. Jf a means were 
devised by which farmers could buy practically undiluted plant food 
and make up their own mixtures, an enormous saving would be 
effected, and any method that would decrease the amount of inert 
matter carried in fertilizers would be of great benefit to the agricul- 
ture of the country. The quantity of filler used is only a minor 
phase of this problem, but perhaps the part of it which is most easily 
susceptible of improvement while the present general methods pre- 
vail in the industry. 
SULPHURIC ACID AND ACID PHOSPHATE. | 
Some of the fertilizer manufacturers produce their own sulphuric 
acid, while others buy sulphuric acid. Of the 425 companies for 
which this office secured returns, 68 were producers of sulphuric acid. 
These firms used the quantities of pyrites and sulphur shown in 
Table II in the production of sulphuric acid for the periods to which 
_ the schedule refers: 
TasBLe Il.— Materials used in the manufacture of sulphuric acid. 
[2,000-pound tons.] 
aes 
- ry o June 
Material. 1917, inclusive, 
Poyseehes tee eee otc os Feet Let Me 1s acta Mee, SUN te Se ator ee ee 585, 317 244,154 
Siig Ee Supe Sct sshd es ono sacsa se 550s ces 98 ee Sean oed = sro s So oeecooscsseesss5Ec¢ 104, 556 85, 625 
The proportion of sulphur used during the first six months 
of 1918 was much greater than the corresponding proportion dur- 
ing 1917. In pre-war times Spanish pyrites was practically the 
only source of sulphuric acid, as pure sulphur was too expensive 
to be used in the manufacture of the acid, but owing to lack of 
shipping facilities, caused by the war, it became very difficult to 
obtain pyrites from Spain; on the other hand, the price of sul- 
phuric acid advanced decidedly as a result of the demand for the 
acid by manufacturers of munitions, so that 1t became profitable to 
make the acid out of pure sulphur. Domestic and Canadian sources 
of pyrites were utilized, but they were not sufficient to supply the 
demand. In addition to sulphur and pyrites, a certain amount of 
nitrate of soda is used in the manufacture of sulphuric acid, but 
the schedules did not call for the uses to which nitrate of soda was 
put, and there is no way of determining how much was used in con- 
nection with the acid chambers and how much went into mixed fer- 
tiizers. Beginning with July, 1918, the Nitrate Committee of the 
Ve 
