AN ANIMAL PIGMENT CONTAINING COPPER. 
523 
which had been employed in the six estimations of nitrogen by Dumas method, 
to which reference has already been made, as discrepant and low. The results 
obtained by Dr. Matthews were as follows :—1 centigrm. of turacin, dried for 
15 hours at 100° C., was mixed with soda-lime and burnt in a stream of hydrogen. 
The contents of the nitrogen-bulbs (previously faintly acidulated with hydrochloric 
acid), were diluted to 250 c.c,, and then Nesslerized. 
i. 50 c.c. required 13‘5 c.c. of a solution of NH^Cl, 1 c.c. of which = '00001 gram of 
nitrogen ; result = 675 per cent. N. 
ii. 10 c.c. required 275 c.c. ; result = 6'825 per cent. N. 
A second combustion was made of the same amount of turacin, the same solutions 
being employed. 
iii. 50 c,c. required 13*55 c.c. = 6775 per cent. N, 
iv. 10 c.c. required 275 c.c. = 6'87 per cent. N. 
The mean of these four percentages is 6'8, or, when corrected for ash, 6'87. Before 
considering the value of this number it will be advisable to give some results obtained 
by means of Kjeldahl’s process. My friend, Professor Kinch, of Cirencester, having 
had great experience with this method, was good enough to make two estimations of 
nitrogen in turacin by its means, using the identical sample which had been employed 
by Dr. Matthews. Here are the results :— 
i. *1718 grin, turacin gave '01335015 grm. NH 3 = 6'399 per cent. N. 
ii. '3075 grm. turacin gave '0236034 grm. NH 3 = 6'321 per cent, N. 
The mean of these two results, when corrected for ash, becomes 6'419, In the face 
of the higher percentages obtained by other methods, and of the known difficulty in 
oxidising turacin completely, I incline to regard this figure as too low. 
We are now in possession of five pairs of nitrogen determinations, all made with 
great care and by methods differing more or less in character. The percentages 
obtained, duly corrected for ash, are arranged in this table. 
Series A. 
Series B. 
Series 0, 
Series D. 
Series E. 
By Dumas’ 
By soda-lime and 
By soda-lime and 
By soda-lime and 
By Kjeldahl’s 
method. 
platinum. 
standard acid. 
Nessler. 
method. 
i. 7-01 
i. 717 
i. 7 23 
i. 6"855 
i. 6-453 
ii. 6-82 
ii. 7*01 
ii. 7’38 
ii. 6 - 895 
ii. 6-384 
Mean 6'92 
7-09 
7-30 
6-87 
. 
6-419 
3 x 2 
