394 ^^6 Philippine Journal of Science leis 



tariff regulation. As yet the only product in the Philippines 

 has been coarse salt, for there has been sufficient demand from 

 tiendas and packers to consume it entirely as such. 



SALT MILLING 



So far as we have been able to determine, there have been no 

 attempts at salt milling in the Islands. A short description of 

 this process may not be out of place. 



Each mill is constructed with one or more sections containing a drier, 

 several sets of rolls, fans, shaking sieves, etc. The modern plants use 

 rotary driers consisting of two concentric cylinders clamped together and 

 rotating on bearings which support the outer cylinder. The inner cy- 

 linder, or steam drum, is about 1 meter in diameter and is fed with 

 live steam. The outer cylinder is about 2 meters in diameter and 15 

 meters long, through which hot air is blown. The dryer is set at an 

 inclination of about 3 or 4 degrees. The salt is fed into the space between 

 the two cylinders at the upper end, and as the drier revolves the salt 

 slowly travels toward its lower end where it is discharged. It is then 

 carried to the first set of rolls. After passing through these, the crushed 

 material is sent over a shaking sieve, which acts as a separator, allowing 

 the fine stuff to go to the bagging room, while the coarser material is 

 conveyed to a second set of rolls, which are set closer than the first and, 

 therefore, give a finer product. This is again sieved, separated, and 

 crushed in still finer rolls, the process continuing until the material has 

 passed through several sets of rolls of increasing closeness, passing over 

 sieves after each crushing. Salt of various coarseness is produced by the 

 use of sieves of varying mesh which feed into different bins. Fans are 

 placed over the top of each sieve and also in the rolls and driers. These 

 fans take off the very lightest and finest material, and their product is 

 conveyed into a room where it is pressed for cattle feed. As the mag- 

 nesium and sodium sulphates are considerably lighter than the sodium 

 chloride, the use of these fans takes out much of the sulphates and purifies 

 the salt very appreciably, as demonstrated by analysis. 



Few statistics of the salt produced in the Philippines have been 

 kept, and it has been necessary for us to gather ours partly by 

 letter. Some manufacturers returned replies very complete, 

 others very lacking in essential features, though we believe all 

 are fairly satisfactory with regard to output. We have carefully 

 studied the plants in Obando, Malabon, Las Piiias, Paranaque, 

 Bacoor, Kawit, and the principal producing towns of Pangasinan. 

 In many places a suspicion that we were gathering data as a 

 basis for taxation kept the men engaged in the industry from 

 giving information freely. Since there is no basis of compar- 

 ison, it is impossible to prove a large increase in the local pro- 

 duction. Information from municipal presidentes shows that 

 there were 105 municipalities representing 30 provinces where 

 salt is manufactured and that in round numbers 19,000,000 



