152 Reviews. [Jan., 



first principles of chemistry, can easily determine what are the 

 properties of any particular water, and whether it will be fit to drink 

 or not. A ready way of detecting the amount of organic matter, and 

 one that is recommended by Dr. Parkes, is by the addition of per- 

 manganate of potash. The amount of permanganate destroyed is. the 

 measure of the organic matter in the water. This is even made 

 obvious to the eye without any weighing, where a series of waters 

 have to be examined ; the permanganate losing its beautiful pink 

 colour when decomposed. All ready methods of detecting the com- 

 position of water are of great importance to an army on the march. 

 It is not always that clear waters are to be trusted. The notorious 

 pump in Broad Street, Golden Square, London, yielded water perfectly 

 clear, and was the most popular pump in the district, yet its waters 

 killed 500 people in the three first nights of September, 1854. The 

 cause of this dire calamity was the communication of a broken drain 

 from a cesspool with this well ; but the water at the time it was drunk 

 gave no signs of this contamination. After such a dreadful accident 

 as this, in a district otherwise well supplied with water by public 

 companies, it would have been thought that this and the other surface 

 well-pumps would have been closed. But no, there it still stands as 

 a memorial of the difficulty of instilling into the public mind, the 

 necessity of obeying sanitary laws, although enforced by such awful 

 examples as this. 



From water we come to air. Dr. Parkes has treated this subject 

 in the same comprehensive and exhaustive manner as the other. Air 

 is more important to life than water. Impure air is a source of more 

 disease than impure water, at the same time its dangerous effects are 

 slower in their action. The impurities of water either produce sudden 

 disease, or their effects pass off before the next dose is taken ; but the 

 effects of impure air are cumulative, as well as sudden and disastrous. 

 Typhus, smallpox, scarlet fever, measles, are all born of impurity of 

 the air, as well as scrofula, consumption, and a host of diseases con- 

 nected with the existence of the state of the system in which they 

 come on. The importance of this subject is only beginning to attract 

 attention, and amongst the most intelligent classes there is only a 

 glimmering consciousness that impure air may become a source of 

 disease. In our great towns, and in the majority of our populations, 

 no knowledge of the practical value of this question seems to exist. 

 Masses of men, women, and children are huddled together in dwelling- 

 houses, whilst our workshops, and shops lighted with gas, are crowded 

 with work people, and the result is a frightful mortality. But neither 

 the costliness of this neglect in an economical, nor its wickedness 

 in a moral, point of view, seems to produce any impression. London, 

 with its teeming population, thus loses thousands of lives annually, 

 and yet is the seat of a legislation, which for weeks debates on the 

 Schleswig Holstein question, and has a press which deplores the 

 fratricidal war in America, but has no measures of relief for those 

 who die for want of fresh air, nor any words of compassion for the 

 slain innocents, and the dying men and women of their own city. 



In his opening chapter on this subject, Dr. Parkes discusses the 



