196 PROCKEDINGS OF THE ROYAL SOCIETY OF QUEENSLAND. 



sulphuretted hydrogen ; reaction, none, neither acid nor 

 alkahne ; residue on evaporation, ash and a shght charring ; 

 free ammonia in considerable amount ; chlorides, equivalent 

 to 16 grs. per gallon ; sodium chloride 26-3 grs. per gallon ; 

 hardness, 8 degrees of temporary hardness ; nitrates, none ; 

 metallic impurities — iron, strong trace; zinc, lead, copper, and 

 arsenic absent; oxygen absorbed in 15 minutes at .212° F., 

 1-30 grs. per gallon ; microscopic examination, grass and weeds 

 in all stages of putrefaction ; bacteriological examination, 

 innumerable colonies. 



These last two findings might have been expected owing 

 to the time which would necessarily elapse between the collect- 

 ing of the sample and its examination. The analysis suggests 

 that the sample originally contained a considerable amount of 

 organic matter. 



Marsh (1908, p. 905-6) has pointed out that there is as yet 

 no sure method of determining bj^ chemical tests whether water 

 is suitable for fish-life. The ordinary " sanitary analysis" 

 determines whether water is fit for drinking and for domestic 

 use, but water which may be j)assed as suitable for such purpose 

 may kill fish in a short time, and we know that fish can (hrive 

 in waters which on routine examination would be pronounced 

 unfit for human use. Both Marsh (1908) and Shelford (1918c, 

 p. 39 footnote) point out that, in this connection, it is impor- 

 tant that such additional items as acidity or alkahnity, the 

 amount of hydrogen sulphide, carbonaceous material capable 

 of being utilised as food, unusual metals, dissolved air, etc., 

 should be known. 



The most important items in the above analyses seem to 

 be those relating to the amounts of oxygen and carbon dioxide 

 present. The blue colour inside the mouths of affected fishes 

 suggests a deficient oxygenation of the blood, and this may be 

 due either to a diminished amount of oxj^gen or to a greatly 

 increased amount of carbon dioxide, or to both. 



Wells (1913) has studied the resistance of fishes to different 

 concentrations and combinations of oxygen and carbon 

 dioxide. In regard to the latter he j)ointed (p. 329) out that 

 the presence of a liigii and low concentration of CO2 is affected 

 by many factors, such as the amount of vegetation in the water, 

 character of the surrounding soil and incoming Mater, depth of 

 water, season of the year, daily temperature, animals present, 



