364 
Journal of Agricultural Research 
Vol. XI, No. 8 
DIALYSIS OF THE EXTRACTS 
A number of measurements were obtained of the proportion of the 
total phosphorus in turnip extract, which failed to pass through dialyzers. 
In different experiments the dialysis was carried out in the presence of 
an acidity of 0.2 per cent hydrochloric acid, or 2 per cent acetic acid, or 
in an aqueous solution. Thymol or chloroform was used to prevent the 
growth of microorganisms. For a membrane parchment paper, pig’s 
bladder, or chicken’s crop was used. In some cases the diffusate was 
replaced repeatedly with the fresh solvent until diffusion had practically 
ceased, and the amount of phosphorus was then determined directly in 
the dialyzate. Again, when fewer replacements were made, time was 
allowed for equilibrium to be reached, and a deduction was made from 
the phosphorus in the dialyzate of the amount in an equal volume of 
the diffusate, the remainder being considered as colloidal phosphorus. 
In the various experiments there was always less than 10 per cent of 
the phosphorus which seemed incapable of passing through a dialyzer; 
and when the diffusates were replaced many times by fresh solutions 
and a long time was allowed for the final diffusions, all but a few per cent 
of the phosphorus passed through the membrane. 
If it be considered that dialysis separates crystalloidal from colloidal 
phosphorus, it is evident that there is not much of the latter in turnip 
juice. It should be said, however, that enzymolysis may have taken 
place, and of course the possibility of hydrolytic changes caused by the 
solvents should also be recognized. 
Frequently, as will appear later, the main object in dialyzing the tur¬ 
nip extract was to obtain the dialyzates for the purpose of adding them 
to standard phosphate solutions, that an attempt might be made to 
find an analytical method which would completely recover as inorganic 
phosphorus that which was added in a standard solution. 
In one sample, calculated on the basis of air-dried turnips, there was 
in the aqueous extract 43.4 per cent of solids and in the diffusates from 
the same through parchment paper 36.7 per cent; similarly, in the case 
of 0.2 per cent hydrochloric acid, the percentages were 50.3 and 40.2, 
respectively. The crude ash in the aqueous extract amounted to 7.6 
per cent and, in the diffusates from the same, 6.7 per cent; \7hereas in 
the hydrochloric acid solution the percentages were 10.1 and 9.8, respec¬ 
tively. 
DIRECT PRECIPITATION FROM THE EXTRACTS BY VARIOUS 
PRECIPITANTS OF INORGANIC PHOSPHORUS 
When it was found that a large part of the phosphorus in turnips 
was in the water or acid extract, it seemed probable that at least under 
certain nutrient conditions much of it might not have undergone meta¬ 
bolism and thereby entered into combination with organic matter, but 
