MICHIGAN ACADEMY Of" SCIENCE. 
75 
and has been in continual operation since that time. Tests of the tap 
water are made every week by the University of Michigan and have been 
declared safe every time. Previous to the installation of this plant 
notices were posted in the University buildings and in the daily paper 
to boil the water as it was contaminated.” In looking back through 
the records I find that in July, 1911, and March, April and May of 
1912, notices were posted on the campus advising the boiling of the 
water as it was contaminated. 
There are other statements in Mr. Leggetts article with which I can- 
not agree but I will go into these later. However, there is one thing 
which while not connected in any way with this article of Mr. Leggetts 
I wish to bring up at this point. The report has reached me from 
several sources that Mr. Leggett has made the statement that I thorough- 
ly approved of and had heartily indorsed the Model Machine that he 
has devised for water purification. This machine is in the offices of 
the National Air and Water Purifying Company here in Ann Arbor 
and is used for demonstration purposes. The following report speaks 
for itself and is a word for word copy of the one I gave the company 
at the time of the test. 
Ann Arbor, Mich., 
Jan. 11, 1913. 
Mr. E. M. Leggett, 
Ann Arbor, Mich. 
Dear Sir: — I hereby submit my report on the action of ozone on the 
Colon Bacillus as tested by me in vour model ozonizing machine on 
Jan. 3d, 1913. 
The growth on two twenty-four hour agar slant cultures of our labora- 
tory stock culture of B.Coli was washed off with tap water and sus- 
pended in water in the first well of your ozonizing machine and the well 
filled with water from the overhead filter the other three wells being 
empty. Tap water from the filter was then turned into this first Avell 
and ozonized air turned through. As soon as water began flowing into 
the second wel 1 ozonized air was turned on here. Similarily when water 
began flowing into the third and fourth wells ozonized air was turned 
on in them. 
Time period between turning ozonized air and water into the first 
well and purified water coming from the fourth well was four minutes. 
One-tenth C.C. of water from the first well before turning on ozone, 
plated on Conradi-Drigalski media showed at the end of 48 hours in the 
incubator, acid reaction of the entire plate and colonies too numerous 
to count. 
Thirty seconds after water began flowing from the fourth well or 
four and one-half minutes after starting ozone and water through the 
first well, one C.C. on media as above showed no growth. One C.C. 
samples plated at the end of one minute and seven minutes gave identical 
results. 
I do not know the volume of water that will pass through ibis ma- 
chine in a given time, neither do I know the volume of ozonized air 
used nor the ozone content of the same. The amount of organic matter 
used in this test was probably comparatively low as the water is said to 
