98 
Proceedings of Royal Society of Edinburgh. [sess. 
Present Investigation. 
The object of the present investigation is to elucidate the question 
of the nature of the relationship of the excretion of allantoin to 
the administration of thymus gland. 
A. Methods. 
1. Methods of Analysis. 
(A) Allantoin Estimation. 
The following methods were tried and rejected : — 
(a) Loewi’s method (16) — a method which depends upon the pre- 
cipitation of the nitrogenous compounds by means of mercurous 
nitrate without precipitating allantoin — is unsatisfactory owing to 
the fact that mercurous nitrate, if too acid, or if impure (containing 
mercuric nitrate) will also precipitate allantoin. 
( b ) The second method — that of Moscatelli (17) — consists in the 
precipitation of allantoin with mercuric nitrate. 
The subsequent washing of the precipitate was found to result 
in considerable loss. 
Another cause of loss is the addition of too much ammonia, by 
which the allantoin nitrogen is set free. 
(c) The next method adopted was that of Poduschka (8), of which 
the following is a description : — 
A measured quantity of the urine is precipitated with basic lead 
acetate, and the excess of lead is removed from a definite volume 
of the filtrate by concentrated sodium sulphate solution. To a 
definite volume of the second filtrate 5-10 per cent, silver nitrate 
solution is added. This is filtered, and 1 per cent, dilute ammonia 
is added to the filtrate, and the precipitate is washed with 1 per 
cent, sodium sulphate solution until free from ammonia, and the 
allantoin is estimated by Kjeldahl’s method. 
The difficulty with this method is to render the precipitate free 
from ammonia. 
If the precipitate he hot free from ammonia, then the nitrogen 
of the added ammonia would be estimated as allantoin nitrogen. 
To render the precipitate ammonia-free it must he washed with 1 
per cent, sodium sulphate until the alkaline reaction to red litmus 
