ee sale = le ae 
SEPTEMBER 15, 1899. ] 
the light from a star, an instantaneous photo- 
‘graph may be taken of a sound wave moving 
across the field of view. 
Professor Wood has in this way obtained 
photographs showing the wave-front forms 
which occur in various cases of reflection, re- 
fraction and diffraction. An auxiliary electric 
spark is employed as a source of the sound 
waves to be photographed. 
THE HYDROLYSIS OF STANNIC CHLORIDE. 
SoLutions of stannic chloride show abnor- 
mally low freezing points. Mr. Wm. Foster* has 
shown that this abnormal behavior is to be as- 
cribed to the hydrolysis of the stannic chloride, 
namely, the formation of HCl and stannic 
oxide, so that in dilute solution there is slowly 
formed four dissociated molecules of HCl in- 
stead of one dissociated molecule of SnCl,. 
The freezing-point constant calculated upon 
this assumption is 14.06 and the value observed 
by Loomis is 14.25. 
THE SPECIFIC HEAT OF SOLUTIONS. 
PROFESSOR MAGIE+ has shown theoretically 
that the heat capacity of a solution of a non- 
electrolyte, osmotic pressure being proportional 
to the absolute temperature, is the sum of the 
heat capacities of the solvent and of the solute, 
and he has derived an expression for the change 
in heat capacity of any solution due to change 
in concentration when the relation between os- 
motic pressure and temperature is given. 
In case of non-electrolytes the above-men- 
tioned relation is verified by experiments of 
Marignac and by more acurate measurements 
carried out by the author. Professor Magie 
points out that sufficient data are not at present 
at hand to verify the more general relation 
mentioned above. 
MAGNETISM AND STRETCH-MODULUS OF STEEL. 
STEVENS and Dorsey {| have shown that the 
stretch modulus (Young’s modulus) of iron and 
steel is very slightly increased by magnetization 
in the direction of the stretch. 
W.S. F. 
* Physical Review, LX., p. 41. 
+ Physical Review, LX., p. 65. 
t Physical Review. 
SCIENCE. 
O19 
THE BACILLUS ICTEROIDES AS THE CAUSE 
OF YELLOW FEVER.* 
Sanarelli reproaches me with not being will- 
ing to yield to the evidence in favor of the 
specific etiological role of his bacillus. I am 
not influenced in my scientific conservatism by 
any feelings of jealousy, and shall be ready to 
do full honor to the discoverer when the dis- 
covery is definitely established. At present I 
cannot admit this for the following reasons : 
First. Sanarelli’s bacillus grows readily in the 
culture media employed by me in my re- 
searches, but in nineteen typical cases of yellow 
fever in which I introduced into such media 
blood from the heart of yellow-fever cadavers, 
this bacillus was not present, the cultures re- 
maining sterile in fifteen. In three of the four 
ceases in which a growth occurred, I identified 
the bacillus found as bacillus coli communis 
(my bacillus a). I strongly suspect that some 
of those bacteriologists who claim to have found 
Sanarelli’s bacillus have mistaken for it one of 
the varieties of the colon bacillus. 
Second. In my experiments material from 
the interior of the liver and kidney, containing 
blood and crushed tissue elements from fresh 
cadavers, was added to culture media in which 
Sanarelli’s bacillus readily grows, but I ob- 
tained a negative result (cultures remained 
sterile) in 30 out of 43 cases. 
Third. Sanarelli’s bacillus is fatal toe guinea- 
pigs and rabbits when injected subcutaneously 
in very minute doses. In my experiments 
blood from the heart and crushed liver tissues 
from the fresh cadaver failed to kill eight out of 
ten guinea-pigs and seven out of eight rabbits 
experimented upon. I admit that the value of 
these experiments is impaired by the fact my 
laboratory facilities did not permit me to keep 
these animals under observation as long as was 
desirable. 
Fourth. The experiments made by Drs. Reed 
and Carroll at the Army Medical Museum, 
show that Sanarelli’s serum in high dilutions, 
(1-100,000) causes arrest of motion and typical 
agglomeration (Widal reaction) of theb acillus 
of hog cholera ; also, that serum from an animal 
immunized against hog cholera, in high dilu- 
*From a reply to Professor Sanarelli, by Dr. George 
M. Sternberg, published in the Medical News. 
/ 
