b6 KOTES AND ABSTKACTS IN CHEMISTRY AND PHARMACY. 
tons and 10 lbs. of ammonia per head per annum, the average sewage (rain 
included) would contain less than 4 grains of ammonia per gallon, and only Id^ 
worth of constituents per ton. According to the authors’ calculations, one ton of 
Peruvian guano would represent 3050 tons of such sewage. The remaining 
chapters of this memoir are devoted to a consideration of the crops to which 
sewage is applicable, and the results of direct experiment and of common prac¬ 
tice in the utilization of sewage. The following are the general conclusions 
which the authors draw from their investigations :— 
1. It is only by a liberal use of water that the refuse matters of large 
populations can be removed from their dwellings without nuisance and injury 
to health. 
2. That the discharge of town sewage into rivers renders them unfit as a 
water supply to other towns, is destructive of their fish, causes deposits which 
injure their channels, gives rise to emanations which are injurious to health, 
is a great waste of manurial matter, and should not be permitted. 
3. That the proper mode of both utilizing and purifying sewage is to apply 
it to land. 
4. That, considering the great dilution of town sewage, its constant daily 
supply at all seasons, its greater amount in wet weather when the land can least 
bear, or least requires more water, and the cost of distribution, it is best fitted 
for application to grass, which alone can receive it the year round. It may, 
however, be occasionally applied with advantage to other crops within easy 
reach of the line or area laid down for the continuous application to grass. 
• 5 . That, having regard to both urban and rural interests, an application of 
about 6000 tons of sewage per acre per annum, to meadow or Italian rye-grass, 
would probably, in the majority of cases, prove to be the most profitable mode 
of utilization, though the quantity would have to be reduced, provided experience 
showed that the water was not sufficiently purified; and it is pretty certain 
that the farmer would not pay |(i., and it is even very doubtful whether he could 
afford to pay \d. per ton, the year round, for sewage of the average strength 
of that of the metropolis (excluding storm-water) delivered on his land. 
6. That the direct result of the general application of town sewage to grass 
land would be an enormous increase in the production of milk, butter, cheese, 
and meat; whilst, by the consumption of the grass, a large amount of solid 
manure, applicable to arable land and to crops generally, would be produced. 
7. That the cost or profit to a town of arrangements for the removal and 
utilization of its sewage must vary very greatly, according to its position, and 
to the character and levels of the land to be irrigated. Where the sewage can 
be conveyed by gravitation, and a sufficient tract of suitable land is available, 
the town may realize a profit; but, under contrary conditions, it may have 
to submit to a pecuniary sacrifice to secure the necessary sanitary advantages. 
Action of Magnesium on Metallic Solutions, and its use in Toxicology. 
M. Z. Roussin, in a paper read before the Society of Pharmacy at Paris, 
states that the metal magnesium put in contact with slightly acidulated solu¬ 
tions of proto- or persalts of iron, of protoxide of cobalt, and of nickel or zinc, 
gives rise to a disengagement of hydrogen, and a precipitation in the metallic 
state of the metals from these solutions. Magnesium equally precipitates silver, 
gold, platinum, bismuth, tin, mercury, copper, lead, cadmium, and thallium. 
Aluminium is not precipitated. The salts of chromium and manganese give 
deposits of oxides. Arsenic and antimony are not precipitated from their acid 
solutions by contact with magnesium, but they combine with the hydrogen 
produced by the reaction, and pass oj0f as arseniuretted or antimonetted hydrogen. 
M. Roussin recommends the use of magnesium as preferable to zinc in toxico¬ 
logical examination. It is capable of precipitating all the poisonous metals 
