324 WATER HYGIENE 
cator for fissured or cavernized rocks. 5. It is also available in gravels, where 
it has been used with success. 6. It progresses at a slightly lower rate than the 
water in which it is suspended. 7. It is not decolorized by passage through 
sand, gravel, or manure; it is slightly decomposed by calcareous soils. 8. It is 
entirely decolorized by peaty formations and by free acids, except carbonic acid. 
Trillat (1899) states and claims that fluorescein can be detected 
in dilutions of 1 part in 2,000,000,000, but that before the dye is used a 
study of the soils should be made with regard to the presence of matters 
which decompose it. Marboutin (1901) comes to somewhat similar 
conclusions. Martel (1903) shows that fluorescein even in very con- 
centrated solutions decolorizes rather quickly after being kept in the 
sunlight. When it is kept in complete darkness, which would be the 
case in the earth, it did not change even after long periods. 
Gehrmann (1913) reports that Alba Orlandi and Roudelli, who used 
a suspension of B. prodigiosus, found that cultures of this organism 
poured on the ground passed through soil 200 meters, and Pfulil found 
that it took the same organism a short time to pass through 24 ft. of 
.gravel. Gehrmann also reports a place at which wells 200 to 300 ft. 
deep too near an old canal were subject to entrance of contaminated 
water; no experimental data are given. 
Meruops oF TREATMENT 
After attempting to use a great many different compounds and 
methods the use of calcium hypochlorite and liquid chlorine is well 
established. 
Traube (1894) proposed the addition of bleaching powder to water. 
Since that time the use of hypochlorite has greatly extended in sanitation. 
Water to which this compound is added in the usual amounts is quite 
harmless. Professor Hulett, testifying in the Jersey City case, that in 
the Jersey City water to which had been added 10 lbs. of bleach per 
million gallons of water he was unable to detect the presence of free 
chlorine. Theoretically, it was possible for free chlorine to be present 
to the extent of 6.4 parts per trillion. It was also revealed that for a 
person to get a medicinal dose such as given in typhoid fever it would 
be necessary to drink 2,500,000 gals. of water so treated. This, with 
other data, indicates that there can be little objection to using a water 
which has received the usual amount of calcium hypochlorite. The 
waterworks officials have received all kinds of objections against the use 
of this chemical for water treatment. Some even claim that they can- 
not raise flowers of a certain tint on account of the chlorine in the water. 
