134 WATERING HORSES. 



into temporary hardness and permanent hardness. Temporary 

 hardness is due to the presence of carbonate of lime and to a 

 lesser extent to that of magnesium carbonate, both of which 

 are soluble in water containing carbonic acid. Hence, when 

 temporary hard water is boiled, the carbonic acid is driven off 

 and the hardness disappears by reason of the precipitation of 

 the carbonate or carbonates, as the case may be. Permanent 

 hardness is caused by salts which are not precipitated by 

 boiling. The best example of soft water is distilled water, 

 and, after that, rain water and river water. Spring water 

 and well water are generally hard. Mr. Thomas Hawkesly, 

 the engineer, points out that at least 80 per cent, of 

 the surface of the globe yields hard water. Letheby con- 

 siders that moderately hard water is best for the drinking, 

 purposes of human beings. My experience leads me to form 

 the same opinion of hard water for horses, provided that the 

 hardness is temporary. " The presence of dissolved solid 

 matter in the water also influences its taste, preference being 

 generally expressed for those waters which are not exceed- 

 ingly poor in such solids " (Bloxani). Besides, carbonic acid 

 gas is always an agreeable addition to drinking water, and 

 as carbonate of lime is readily soluble in water containing 

 that gas, it can hardly fail to be present in natural water 

 in which that gas is dissolved. All natural water which is 

 palatable to human beings, and most probably to horses, 

 is hard. The preference sometimes evinced by horses for 

 muddy water is, I think, due as a rule to deficiency of 

 mineral matter in the food of these animals, and if that 

 be the case, it cannot be reasonably urged as an argument 

 in favour of the employment of such water for the drinking 

 purposes of horses which are kept under healthy con- 

 ditions of food. The deficiency in question is usually that 

 of common salt. When water is brought by leaden pipes, 

 there is less danger of lead poisoning with water which con- 



