508 REPORT OF THE HARVARD AFRICAN EXPEDITION 
Dukwia River (Firestone Plantations Company ‘‘Du No. 3’’). The river water 
at that time was slightly cloudy and ten ampoules of calcium hypochlorite were re- 
quired to give a test for adequate chlorination in thirty gallons of water. When, 
after rain, the river water became more turbid, twelve or fifteen ampoules would 
be required to give a faint taste of chlorine, but tests with orthotolidine did not 
even then show an adequate excess of chlorine. At this rate the supply of Army 
calcium hypochlorite would very soon have been exhausted had its use been 
continued. 
The turbidity of the water was probably caused by very finely-divided mineral 
matter, but, even after rain, there was very little sediment on standing. 
(II) Burroughs Wellcome & Co.’s tabloids of ‘chlorinated lime” were then 
tried. Directions are provided with their “water sterilizer.” They specifically 
do not recommend this product for use in the tropics. We were not surprised, 
therefore, to find evidence of early deterioration in their caletum hypochlorite. 
The tablets served well for a month, and less well for several months longer, but 
increasing numbers of tablets had to be added until the water toward the bottom 
of the container became milky with lime. Within a few weeks the bottles 
began to pop when opened. Later, liberation of chlorine within the bottles lifted 
the cork stoppers and cracked the paraffin sealing. Finally, the tablets turned 
grayish and became soft. At this stage they were practically inert. 
The Burroughs Wellcome and Co. test tablets of potassium iodide and starch 
soon began to give results which were at variance with those of the orthotolidine 
test. Both tests were soon abandoned in practice, and we came to rely instead 
upon the taste of chlorine. At the same time we entirely discontinued dechlorina- 
tion of the water, because the taste of chlorine was not seriously objectionable and 
this evidence of its presence gave an added sense of security. 
On account of the difficulty of adequately chlorinating turbid water, we came 
to rely more and more upon boiling any water which was not clear. 
(III) The calcium hypochlorite which we had packed in vials with rubber 
stoppers sealed with paraffin was not used. When examined after eighteen 
months (the Expedition had returned home meanwhile) it was found that all 
the stoppers had become loose, that some had fallen out, and that the cigarette 
tin in which the vials had been packed was badly damaged by rust. Doubtless 
the corks had been loosened by decomposition with gas formation within the 
vials. 
(IV) The halazone tablets were very useful in Liberia for chlorinating water 
in canteens while on the march. In the Belgian Congo they were again used for 
chlorinating filtered water in carafes upon river steamers and at the hotel at 
Stanleyville. Three or four tablets from a recently opened bottle regularly gave 
a strong taste of chlorine when added to a quart of clear or filtered water. While 
on safari in the Eastern Province of the Belgian Congo, the water encountered 
was generally so turbid as to render chlorination unsatisfactory. Consequently, 
boiling was regularly practiced there. It was not difficult, because the party had 
been divided into sections which travelled separately. 
Some of the halazone tablets were extremely friable when packed and others 
