376 



Or, 



Carbonate of soda 54 



Sulphate of lime 68 



Carbonate of lime 20 



Total 142 



Let not the non-chemical engineer rashly conclude that 

 the members of his kindred profession have no rules for 

 their guidance, that there are no points on which they are 

 agreed; still less, that chemical analysis is an unessential 

 matter, purely theoretical, and definitively settled. 



While the controversies between the partisans of locomo- 

 tive and atmospheric, screw and paddle, broad and narrow 

 gauge, are urged with their present talent on either side, 

 and remain in their present state of indecision and absence 

 of conviction to each other, engineers may look with charity 

 upon those divisions which are not only more speculative 

 than practical, but rather apparent than real. For chemists 

 know immediately what is intended, and, different as to an 

 unpractised eye the two statements may appear, to the 

 chemist it is not the actual composition of the water which 

 differs, but the language in lohich the results are stated ; and 

 he translates with facility that mode of expression used by 

 another chemist into that which he is accustomed 'to employ. 

 The reason of this difference in expression is, that when 

 water is concentrated by evaporation, almost to dryness, the 

 acids and bases present, however combined originally, and 

 whether in a natural water, or introduced as salts in any 

 specified order of arrangement, form ultimately those com- 

 pounds which are least soluble in water. Excess of carbonic 

 acid, if present, is at the same time disengaged. 



He, therefore, who either states the salts which he has 

 actually so obtained by evaporation, or, having ascertained, 

 by the same methods as others, the quantities of acids and 



