N. MATERIA MEDICA, THERAPEUTICS, AND HYGIENE. 565 



inner surfaces of these tubes, notwithstanding that one of 

 them had carried water for two hundred years, were com- 

 pletely intact. 



Direct experiments upon the same question have also been 

 carried out by Leblanc, agreeing well with those made by 

 Dumas many years ago. Distilled water was found slightly 

 to attack the lead ; while river, spring, and rain water had 

 no appreciable action on the metal. 8 C\ January 29, 1874. 



METHOD OF PURIFYING WATER. 



In the preparations for the campaign on the part of Great 

 Britain against the Ashantees, on the Gold Coast of Africa, 

 due precautions were taken in reference to the health of the 

 troops; and as the waters in that region are known to be 

 very bad and deleterious to health, the services of men of 

 science were'invoked for suggestions as to the proper mode 

 of purifying them. In an article prepared in this connection 

 by Mr. William Crookes, and published in the Chemical JVeics, 

 various methods of purifying water for military purposes are 

 detailed, and the conclusion is reached that the only substance 

 that will be practically available is the sulphate of alumina, 

 which has the power of converting all organized animal mat- 

 ter, living germs, etc., into an insoluble substance like leather, 

 and probably destroying their vitality, at any rate permit- 

 ting the precipitate to be filtered. This precipitation takes 

 place with great rapidity if fine clay be used with the sul- 

 phate, and filtration is then not required, as the clear water 

 can be poured off" from the sediment in the course of a quar- 

 ter of an hour. 



Mr. Crookes refers to a mixture of alumina, clay, and char- 

 coal, which is known by the name of A B C compound, and 

 is used by the Native Guano Company of England for the 

 purification of sewage, and with so great success that the 

 most offensive-looking and foul-smelling liquid is, in a quar- 

 ter of an hour, converted into a bright, clear, inodorous, 

 tasteless water, non-putrescible, and so pure as to allow the 

 most delicate fish to live and thrive in it. 



The application of these facts and principles is suggested 

 by Mr. Crookes, the charcoal being omitted, however, and its 

 place supplied with a permanganate; and he gives the follow- 

 ing as the elements of a suitable mixture: namely, 1 part of 



