372 The Philippine Journal of Science i9i4 



The commonest purpose of technical analyses in the Philippines 

 is the determination of the fitness of water for the production 

 of steam, for the purity of the water to be evaporated is recog- 

 nized as a very important factor. The manufacturing industries 

 in the Philippines are generally in an undeveloped state, and few 

 specific troubles have been encountered that can justly be ascribed 

 to the water. Most of the establishments, particularly those at 

 Manila, have had little or no trouble in obtaining an adequate 

 supply of suitable water. Many of the industries, of which tan- 

 ning is an example, are carried on in such primitive fashion that 

 the question of the quality of water used seldom comes up for 

 consideration, but this question will become more and more sig- 

 nificant as manufacturing industries develop. 



The chemical composition of a feed water plays an important 

 part in the formation of scale and sediment, in the corrosion of 

 metals, and in the causing of priming and foaming. Few natural 

 waters are entirely suitable for boiler use without previous 

 treatment. Even distilled water may have a corrosive action on 

 boiler parts. Rain water, or a heavy fall of snow melting quickly 

 on watersheds, is sure to give to its drainage rivers a water which 

 has a highly corrosive action when used in boilers.-' 



CONSTITUENTS 



The following classification shows the effect of different ingre- 

 dients in boiler waters : 



Calcium carbonate (CaCOa) 



Magnesium carbonate (MgCOa) 



Calcium sulphate (CaSOO 



Magnesium sulphate (MgSO.) ^ ^ause scale formation. 



Silica (SiO.) 



Iron oxide (FeaOj) 



Aluminium oxide (AUO.) 



Grease, suspended matter, mud 



Sodium chloride (NaCl) in the presence of\ 



calcium and magnesium salts 

 Magnesium chloride (MgCL) (due to de-f 



composition of this salt at high temper-) Cause corrosion. 



atures) 

 Calcium chloride (CaCL) 

 Potassium chloride (KCl) 

 Alkali salts Cause priming. 



Calcium carbonate. — Calcium carbonate is almost insoluble in water. 

 Water containing carbonic acid dissolves calcium carbonate more freely on 

 account of the formation of the more soluble bicarbonate, and this is the 



"Kent, Steam Boiler Economy. J. Wiley and Sons, New York (1901), 

 313. 



