1900-1901.] Prof. Letts and Mr Hawthorne on Ulva latissima. 271 
bator at blood heat. Under these circumstances gases began to 
come off in 48 hours, and were then rapidly evolved. 
The following analyses were made : — 
Analysis of Gases evolved from Ulva latissima fermenting in 
Sea Water. 
I. 
II. 
(Collected 5 days 
(Collected 12 days 
after incubation, 
after incubation, 
at 37° C.) 
at 37° C.) 
Volume of gas taken, 
. 14*0 c.c. 
16-55 
After addition of potash, . 
. 8*0 „ 
8*45 
„ py™> • 
. 8*0 „ 
8-45 
Oxygen then added, 
. 13*7 ,, 
11-55 
After explosion, 
. 10*0 „* 
7-65* 
C0 2 found, 
. 6*0 c.c. 
8-10 
0 2 j > 
. none 
none 
H 2 ,, 
7 '8 c.c. 
8-23 
N 2 „ . . . 
. 0-2 „ 
0*22 
14'0 c.c. 
16-55 
Percentage composition. 
C0 2 
. 42*8 c.c. 
48*94 
H 2 
. 557 ,, 
49-73 
N 2 
. 1-5 „ 
1-33 
lOO’O c.c. 
100-00 
Ho sulphuretted hydrogen was present in the gases, which, as 
their analyses indicate, consisted entirely of carbonic anhydride and 
hydrogen. Owing to the solubility of carbonic anhydride in water, 
it was to be expected that the gases collected at first would con- 
tain a lower proportion of this constituent than was actually 
evolved. Only when the liquid in the flask had become saturated 
with carbonic anhydride would the gaseous products of the fermen- 
tation make their way into the collecting tube in their proper 
proportions, and this state appears to have been reached when the 
second analysis was made. Its results show the carbonic anhydride 
and hydrogen to be present practically in the same proportions 
by volume or in equi-molecular proportions. 
The gas remaining after explosion contained no C0 2 . 
