CHEMISTRY AND PHYSICS. 51 
The arrangements also should be such as to retain the property of purifying water 
for a considerable length of time without deterioration.”’ 
It is needless to state that this ideal purification of water has not been even 
approached by any known system of filtration in use. Such being the case, 
it is allowable to assert that no such system of filtration is possible; from which 
it follows that the solution of the problem of water purification to the above 
standard must be sought for outside of present methods, and that any process 
for the removal of injurious impurities in solution in water physically and chemi- 
cally latent will be incomplete unless means are provided for rendering all such 
substances fit for removal by filtration or by sedimentation by making them in- 
soluble and causing them to coagulate and unite with other impurities in 
suspension. 
With the above high ideal of water purification as a standard, the writer has 
invented an apparatus and a process which in combination provide for the fulfill- 
ment of the above conditions. 
The apparatus consists essentially of one or more vessels, tanks or reservoirs 
of any desired form or required capacity, with one or more oxidizers to each 
tank. These oxidizers are composed of metallic iron and coke arranged to form 
a galvanic battery, the size and number of oxidizers to depend on the dimensions 
of the tank, together with the requisite systems of piping for filling the tanks with 
water, agitating with air, drawing off the purified water, and removing the sludge 
whenever by its too great accumulation it is found necessary. 
PROCESS. 
The process fulfills the requirements above enunciated by Dr. Lewin of remoy- 
ing all objectionable impurities in water whether in suspension or in solution, and 
that, too, without deterioration of the apparatus; and consists __ 
1st. By the use of chemical reagents, changing all substances in solution in water 
to an insoluble state in suspension. 
2d. By combination of the galvanic action of the oxidizer, the salts of iron. 
- and aeration; these substances, now all in suspension, by coagulation and aggre- 
gation, are fitted for being precipitated by sedimentation. 
REAGENTS. 
The reagents for rendering the earth salts, held in solution by the solvent acid 
gases in the water, insoluble in suspension are alkalis for which the solvent acid 
gases have a greater chemical affinity than they have for the earth salts held in 
solution by them. The withdrawal of these acids renders these earth salts in- 
soluble. e 
The reagents for changing organic substances in water, rendered soluble by 
putrefactive fermentation, insoluble are metallic iron, coke, and salts of iron. 
3d. The treatment consists in introducing into the tank the requisite amount 
of alkali necessary to absorb the carbonic acid holding the earth saits in solution, 
then fill with water; during the time of doing so and for the necessary length of 
time after, by means of compressed air, force the water through the oxidizer. 
This, in addition to thoroughly mixing the reagents with the water by bringing 
each particle of water into intimate contact with the material of the oxidizer, 
oxidizes or burns up the organic matter in solution in the water, thus render- 
ing it insoluble; in addition to which the galvanic action of the oxidizer in the 
water kills the bacteria and causes the impurities in the water to coagulate. 
After completion of reaction, test for excess or deficiency of reagents and correct 
to neutrality if necessary. Then add reagents to absorb the sulphuric acid, and 
again agitate, test, and correct. After completion of reactions to neutrality, add 
