68 REPORT — 1851. 



in fact the soil would require to be impenetrable. To inhabit a place for a 

 few months would be to make it unhealthy. Instead of such a result, we 

 have the soil of towns, which have been inhabited for centuries, for a time 

 longer than history can tell us of, in a better state than the soil round many 

 a country-house. St. Paul's churchyard may he looked on as one of the 

 oldest parts of London, I suppose ; the water there is remarkably free from 

 organic matter, and the drainage of the soil is such that there is very little if 

 any salts of nitric acid in it. A well at Tower Hill was in a similar condi- 

 tion, but not so thoroughly nitrated. Of course there are parts of a town 

 Avhere the matter becomes too great to be managed well, and being combined 

 with bad drainage, even the active state of the subsoil, which seems to do 

 its utmost to destroy all the elements of disease which enter into it, is not 

 sufficient to remove the amount continually supplied to it from some hundred 

 acres of closely-built ground. Even in these cases however we are more 

 surprised at the comparative purity of the subsoil than at the impurity. As 

 it is, the impurity of the subsoil in certain parts of towns requires proof; and 

 although proof can be got and is got, without this action of the soil the 

 proof would stare us all painfully in the face and hunt us out of its vicinity. 

 It has become necessary to prove the great amount of evil resulting from 

 burial in towns, whilst the enormous amount of organic matter has disap- 

 peared rapidly from our view, and the evil seems only to become distinct to 

 us when the mould of the churchyard has become in a great measure the 

 remains of organized beings. 



If soil has such a power to decompose by oxidation, we want to know how it 

 gets so much of its oxygen, and here there appears a difficulty ; we must, 

 however, look at once to the air as the only source, and see how it can furnish 

 the supply. When water becomes deprived of its oxygen, it very soon takes 

 it up again. If watei' be deprived of its oxygen by the use of sulphate of 

 iron, so as to make a white precipitate of protoxide of iron, or if it be de- 

 prived of it by boiling, and a little white precipitated protoxide of iron placed 

 at the bottom, it will be found that a few minutes will give some colour to the 

 iron. It will pass through the blue and almost black stages to the yellowish 

 brown, taking the oxygen from the water, which again supplies itself from the 

 air, and is in fact a kind of porous medium for the gas. This shows us readily 

 how the soil may be oxidized, how the nitric acid may be formed under the 

 surface of town soil. We do not in fact find it formed at great depths, but we 

 find it formed in undrained places which have no other source of oxygen. 

 It may seem a trifling matter to explain this, but it was a difficulty to me to 

 see how the oxygen could be collected in some of the almost subterranean 

 circumstances in which it accumulated. Water from wells in a soil like this, 

 continually obliged to force oxidation, is sufficiently objectionable, and it 

 requires no eloquence to deter people from using it when they once know it. 

 Perhaps, however, when the nitrates are in not very large quantities, M'hen 

 they cannot be tasted, the water may be reasonably considered much better 

 than any water with matter in it liable to putrefactive decomposition, and 

 the general testimony of tradition is to consider it so. 



It appears, in fact, that organic matter is incapable of passing deep into a 

 soil ; by conversion into soluble salts it becomes soluble, and by that means it 

 is easily washed away in an inorganic state. When this occurs in the country, 

 the use of it is not so apparent as when it occurs in a town. When there is 

 a great excess of organic matter on the surface of the ground, it does of 

 course decompose, and the results are bad for health ; and if ammonia is 

 formed too rapidly, bad also for the soil, which loses its food for plants. The 

 formation of nitrates prevents the passage of nitrogen into the atmosphere, it 



