Mr, West on Natural Waters. 43 



derance to work, and loss of fuel consequent on letting out the 

 fire, are not the only disadvantages attendant upon the cir- 

 cumstance. The boilers must be more quickly destroyed, 

 from the great heat of the outside being very slowly conducted 

 through the earthy crust. In fact, they told me that for a 

 short time before the usual periods for cleaning, it was difficult 

 to get the steam up, whatever firing was used. Nor is the 

 employment of the Sabbath for this purpose to be left out of 

 the question. The adhesion of the earthy matter to the iron 

 is lessened, and the interval between the cleanings consequently 

 protracted, by the use of potatoes, the pulp of which envelop- 

 ing the crystals, lessens their tendency to cohere, and preserves 

 them for a time suspended in the water of the boiler. 



I have taken much pains with a set of experiments to settle 

 this point, among others, viz., * On the comparative solvent 

 powers of waters holding in solution various salts in different 

 proportions.' I have come to the conclusion, that the earthy 

 salts exert a great influence in preventing the solvent action of 

 water on vegetable substances ; the proportion dissolved by 

 pure or soft water being considerably greater than that by hard 

 water. Portions of tea of the same weight, viz., thirty-six 

 grains after drying, with equal quantities of boiling water of 

 different kinds, standing in similar vessels for the same time, 

 yielded, the hard water, after deducting the weight of the 

 earthy matter, about four grains of extract ; that is, the infu- 

 sion left, besides the earths, four grains, on evaporation to 

 dryness; the leaves again dried weighed thirty-two grains: 

 the extract from the soft, or distilled water was pretty exactly 

 eight grains; the leaves, after drying, twenty-eight grains. 

 Thus, the soft water had extracted from the tea just twice as 

 much as the hard. I made numerous experiments of the same 

 description, but found it difficult, from circumstances con* 

 nected with the absorbent nature of the leaves, to obtain 

 exactly the same quantities of extract and of spent leaves, in 

 repetitions of the same experiment, and cannot, therefore, de- 

 pend on this mode of comparing waters differing little from 

 each other ; and the effect of pure water is certainly very near 

 to that of any natural water containing carbonate of soda. I 

 think, however, that the soda does a little increase the quantity 



