222 



How far these may influence health in distant localities seems 

 not easy to determine. Those containing vegetable and 

 animal matters are positively injurious. The degree of 

 hardness is very material in an economical point of view, 

 as connected with the consumption of soap. I hope by Dr. 

 Clarke's method, (Professor of Chemistry in Aberdeen,) by 

 the soap test and acid test, to obtain the hardness due to 

 both neutral and alkaline earthy salts, of the waters chiefly 

 used in these towns. The waters of Halifax and its neigh- 

 bourhood have already been described by a distinguished 

 Member (Dr. Alexander) of our Society. So also have the 

 waters of Yorkshire been analysed by Mr. West. It would, 

 however, be presumptuous to assert, without more information 

 upon the subject, that any degree of unhealthiness is to be 

 attributed to the difference in the quality of water. 



Exceptions. — The perturbations which, within certain 

 limits, counteract those prevaihng laws of mortality which 

 are produced by general Geological causes are — 1. Density 

 of population; 2. The trades or occupations of the people 

 of each district ; 3. Epidemics, acting partially. 



1. Density In two towns, both having the same Geolo- 

 gical advantages or disadvantages, but the one having twice 

 the population per acre — -this greater density may, I do not 

 say will, within certain limits, alter their rates of mortality. 

 For example, Sheffield has 5,155 persons to the square mile, 

 while Leeds has only 2,416; their rates of mortality are^ 

 nevertheless, the same, i. e. for 1840, 1841, and 1842. But 

 it is absurd to assert that the mortality increases with the 

 density of the districts, as the Registrar- General, in his 

 Fourth Report, page 15, states. Birmingham has a popu- 

 lation of 33,255 to the mile — eleven times as many as Leeds, 

 and five times as many as Sheffield, and yet their rates of 

 mortality are the same. While again Manchester has only 

 9,525 to the mile, and yet its rate, 3.2, is much higher than 

 that of Birmingham, and only second to Liverpool, which is 



