[saurr] PURIFICATION OF PEATY WATERS BY FREEZING 33 
Purification by freezing has long been known, but the data on record 
in this regard refer more particularly to the exclusion of mineral matter. 
The extent to which dissolved vegetable matter may be thrown out by 
freezing, as made evident by these results, has seemed to the writer some- 
what remarkable and worthy of note. 
To obtain some further knowledge respecting this exclusion of peaty 
matter by freezing, 1000 cc. of the Ottawa river water were placed in a 
porcelain basin and submitted to the action of frost until the greater 
portion of the water was converted into ice. Upon removal of the ice it 
was found that 125 cc. of the original water still remained unfrozen, the 
ice representing 875 cc. Analyses of each were made, and the results 
show that under such conditions a very considerable elimination of the 
organic matter had taken place during the freezing process. 
Ice Water 
p.p.m. p.p.m 
HTeCMAMMONIA NE RAR ne re Ol 08 
AND UMNO AMIMNONIR]- o5. ce ee Ne en Sears . .175 .40 
A calculation from these results of the amounts of free and albu- 
minoid ammonia in the original water, furnishes data in close accord 
with those obtained by direct analysis. 
The degree of purification is dependent on several factors. Accord- 
ing to recognized authorities, ice forming on deep water is purer than 
that on shallow water—the quality of both waters being initially the 
same. The slower the ice formation, the purer the ice. The thicker 
the ice, within certain limits, the purer it is; and, lastly, it is held that 
the lower part of the ice block will be of better quality than that nearer 
the surface. 
Purification by freezing is, after all, however, but partial. Un- 
doubtedly under the most favourable conditions a very large proportion 
of the mineral and organic constituents may be thrown out, and the 
bacterial content considerably reduced ; but it has been clearly shown that 
the elimination is never such that the ice cut from a polluted source is 
safe for domestic purposes. 
The investigation has been continued to ascertain the purity of the 
ice in relation to its position in the block, but the data as yet are incom- 
plete and are, therefore, reserved for presentation at some future time. 
Sec. II1., 1907. 3. 
