REVIEWS. 
195 
after the discussion of these several chapters, comes one on the utensils used 
in the preparation and storage of food, and on various methods of detection 
of adulterants. These are followed by a general summary of adulteration ; 
and last, but by no means least, comes a chapter useful to both the medical 
officer of health and the chemical analyst, and that is the Act for the sale of 
food and drugs, which was issued in 1875. 
Out of this enormous list of subjects it is hard to choose any, for all 
appear of almost equal import. However, we may select a few, and first 
of water. This is a form of food which all, whether high or low, have to 
partake of, and it is therefore of the utmost importance that we should have 
the means of detecting the presence of impurity. Indeed, it is the more so 
from the fact that it is now believed to be the medium by which we take 
into our bodies the contagions of cholera, typhoid fever, and possibly also 
scarlatina. We are glad to see, therefore, that Dr. Hassall has given ample 
space to the treatment of this subject. His remarks cover no less than 77 
pages, and deal with every possible question connected with the purity and 
impurity of almost every conceivable form of water. From these we 
select his remarks on the question of filtration. For it is by the filter alone 
that people generally have any control over their drinking-water, and it 
is of great importance that attention should be paid to the following 
statements : — 
“ Of course the powers of all filters are limited, and they speedily become 
spoiled when too much work is thrown upon them at one particular time — 
that is to say, when water containing a large quantity of organic matter, 
say, six or eight grains per gallon, is rapidly passed through them. In 
this case the requisite time is not afforded for the due action of the 
filters, which become simply clogged ; but when water containing only a 
moderate amount of impurity, as one grain per gallon, is passed through, 
then the action of the better filters, especially those containing charcoal, is 
not only satisfactory but continuous.” In regard to the mode of cleaning 
filters, which should be done often, contrary to the usual practice of keep- 
ing them in perpetual action from year’s end to year’s end, Dr. Hassall quotes 
as follows from Dr. Parkes’ able treatise : “ Every two or three months 
(according to the kind of water) four to six ounces of the pharmacopceial 
solution of potassium permanganate, or twenty to thirty grains of the solid 
permanganate in a quart of distilled water, and ten drops of strong sulphuric 
acid, should be poured through, and subsequently a quarter to half an ounce 
of pure hydrochloric acid in two to four gallons of water. This will aid the 
action of the permanganate, and assists in dissolving manganic oxide and 
calcium carbonate. Three gallons of distilled or good rain-water should be 
then poured through, and the filter is fit again for use.” We think it a 
pity that Dr. Hassall reproduced his old cuts representing the fresh-water 
animals, as they convey incorrect ideas at the present time. And we would 
also allude to the objectionable analysis of Messrs. Allsopp’s beer, for 
which Dr. Hassall has had to offer a public apology. 
Under the head of milk and its adulterations we find some very useful 
practical hints, as well as various methods of analysis. But we are not in 
agreement with the author in thinking that sheep’s brains are used in the 
adulteration of milk. However, he gives an illustration showing the ap- 
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