(92) 
is the best of all, has given in the hands of some workers bad results 
with some substances. The same applies to KJELDAHL’s method 
which has now superseded the process of WimLL and VARRENTRAPP, 
but which is still constantly being modified and of which it has 
been proved that it cannot be employed in the case of substances in 
which the nitrogen is combined with oxygen or a second nitrogen atom. 
The great advantages occurring when an organic nitrogen com- 
pounds may be oxidised in such a manner that the carbon and 
nitrogen are estimated in the same portion, have already led to some 
investigations but the methods resulting therefrom are not always 
satisfactory. Those according to which the nitrogen is converted into 
ammonia by the moist process, such as KJELDAHL’s sulphuric acid 
process, do not yield the total carbon as carbon dioxide, so that 
other means have to be resorted to in order to obtain the desired 
result. But neither the electrolytic method of BuppDE and ScHou, 
nor the addition of strong oxidising agents, such as chromic acid, do 
away with the necessity of combining this process with the dry 
method, namely the passing of the gaseous products over red hot 
oxidising substances and the separation of the carbon dioxide from 
sulphur dioxide or sulphuric acid vapour. Even when by this-com- 
bination the estimation of the carbon is satisfactory, the nitrogen 
estimation is not always so and particularly not in such cases where 
KJELDAHL's method does not give good results. Buppr and ScHou 
themselves admit that for cyclic compounds, which have more than 
one nitrogen atom in the ring, their electrolytic method is quite as 
unsuitable as KJELDAHL’s process. This is, however, not quite cor- 
rect, for from the results of former investigators it appears that 
KJELDAHL’s method may give very reliable figures indeed in this 
case. It remains possible, however, that neither the electrolytic 
method nor the use of oxidising agents give good results in cases 
where accurate results are obtained by KJELDAHL's method, as has 
been proved by Miss VAN AKEN in the second instance. 
PauL Frirscu (Liesie’s Annalen 1897, 194, 79) describes a 
method for the determination of carbon and nitrogen in organic 
compounds by the moist process. It is, he says, a combination of 
MESSINGER’s carbon and KRÜGER'’s nitrogen process with a slight 
modification and its essential feature is that the substance is placed 
in strong sulphuric acid and potassium dichromate added in small 
portions at the time. The gas evolved is passed by means of a 
current of air through a red hot tube filled with lead chromate and 
copper oxide and the CO, after having been dried is absorbed in a 
potash apparatus and weighed. From the residue, which is supposed 
