


























= hy 5 
June 2, 1923] 
& 
NATURE 
763 

contact with sulphide of iron is more rapidly corroded” 
than when the sulphide is absent. The action is 
electrolytic, since the presence of the sulphide in the 
same water was without effect unless the iron and 
the sulphide were in direct contact or connected by 
an iron wire.—Pierre Jolibois and Pierre Lefebvre: 
The dehydration of gypsum. Gypsum heated in a 
current of dry air at varying temperatures gives no 
indication of the formation of the semihydrate. 
On the other hand, if heated in steam at 160° C., the 
semihydrate CaSO, . }H,O is formed.—Mme. Pauline 
-Ramart and J. Blondeau: The molecular trans- 
formations accompanying the dehydration of the 
' ares a-a-disubstituted phenylethyl alcohols.— 
. Chaumeil and V. Thomas: Researches on picryl 
sulphide. Study of the binary picryl trinitroanisol 
sulphide.—Raymond Delaby: The action of the 
magnesium halides on the epibromhydrin of ethyl- 
glycerol. —MM. Bordas and Touplain: Specific 
characters of the heavy oils of beechwood creosote. 
The presence of cerulignol in these tars, giving a 
blue coloration in alcoholic solution with lime or 
baryta, suggests that these heavy oils may form a 
suitable ingredient in the mixture used for denaturing 
alcohol.—Maurice Piettre: The estimation of humic 
and fatty materials in the soil by means of pyridine. 
Pyridine is an excellent solvent for humus. Diluted 
with an equal volume of water, it can be used to 
extract and determine the fixed and free humus in 
soil—Ch. Mauguin: The reflection of Réntgen rays 
on certain remarkable reticular planes of calcite. 
The experiments described form a new confirmation 
of the hypothesis of W. L. and W. H. Bragg on the 
structure of calcite——L. Cayeux: The phenomenon 
of imprints in the Mesozoic iron minerals of France. 
So far as the oolitic iron minerals are concerned, 
the impressions may have been caused by pressure 
alone, or by solution with or without pressure effects. 
—Léon Bertrand: The rdéle of the Provengal advance 
folds in the tectonic of the Maritime Alps.—Pierre 
Bonnet: The existence of the Coniacian in the 
Daralageoz massif (Southern Transcaucasia). — 
Americo Garibaldi: Thyroidectomy and immunity. 
A Saag of the results by various workers on 
this subject leads the author to modify the view put 
forward by him in 1920. The removal of the thyroid 
Causes an increased sensibility towards substances 
foreign to their internal medium, but dat the same 
time the defensive power of the organism undergoes 
a marked increase.—M. Tiffeneau and H. Dorlencourt : 
A new series of hypnotics, the aryldialkylglycols. 
These glycols, of which phenyldiethylglycol, 
C,H; . CH(OH) . C(OH)(C,H;)2, may be taken as the 
type, show marked hypnotic properties both towards 
mammals and fishes. These properties are due to 
the glycol group, and are strengthened by tri- 
substitution: they -vary, between certain limits, 
with the number of carbon atoms in the molecule, 
and are modified by the relative positions of the 
substituting groups.—Raphaél Dubois: Gyratory 
antikinesis—P. Vignon: The mimetism of the 
Pterochroza.—Louis Roule: The peculiarities of the 
Rhéne basin with respect to its ichthyological fauna. 
WASHINGTON. 
National Academy of Sciences (Proc. Vol. 9, No. 3, 
March).—H. S. Reed: A note on the statistics of 
cyclic growth. The lateral shoots on a young 
bs branch develop typically in three groups 
along the branch, and their size and number are 
greatest in the group nearest the proximal end of 
the branch. The mean lengths of corresponding 
lateral shoots are symmetrical about a mean for 
each group.—R. A. Millikan: Stokes’ law of fall 
NO. 2796, VOL. 111] 
‘completely corrected. The form of Stokes’ law 
proposed is 
4 _ 6rnav : 
a sia +A‘lja’ 
where F is the force acting, v the velocity produced, 
the viscosity of the medium, //a is the mean free 
path over the radius, and A’ is a factor which varies 
theoretically from 0-7004 to 1-164 as, with decreasing 
density, //a changes from very small to very large 
values and allowance is made for a percentage of 
cular reflection at the surface of the oil. The 
ange in A’ means physically a change from viscous 
resistance to resistance due to molecular impact. 
Experimental values of A’ obtained by the oil-drop 
method in several gases at varying pressures vary 
from 0-864 to 1-154.—-C. Barus: Gaseous viscosity 
measured by the interferometer U-tube. For air, 
a capillary tube is attached to the closed limb of 
the U-tube containing air at slightly more than 
atmospheric pressure. The displacement of the 
interference fringes decreases exponentially with 
time, and the decrease is timed over equidistant 
scale parts of an ocular micrometer. The value 
found for air in a heated room is 0-o00180,.—T. W. 
Richards: Compressibility, internal pressure, and 
atomic magnitudes. Internal pressure is defined as 
the pressure exerted by the force of affinity. Curves 
were obtained, partly by extrapolation, for the 
pressure-volume relations of sodium, potassium, 
chlorine, and bromine, reduced to a gram-atom basis, 
and the atomic diameters of these elements in the 
chloride and bromide of each metal were computed. 
The compressibility of the products calculated from 
these data is said to agree with the experimental 
values. The results are in accord with the theory 
that atoms are subject to different pressures in 
different chemical combinations, and their bulks 
depend on this and on the compressibility of the 
elements concerned.—J. Kendall and E. D. Crittenden : 
The separation of isotopes. As applied to chlorine, 
a solution of sodium chloride in agar-agar jelly is 
made the middle section of a tube used as an electro- 
lytic cell built in three sections each three feet long. 
tween the anode and the chloride is a sodium 
hydroxide gel and solution, and separating it from 
the cathode is a sodium acetate gel and solution, 
the latter containing acetic acid. The boundary 
surfaces remain distinct because the chloride ion 1s 
preceded by a faster hydroxyl ion and followed by 
a slower acetate ion. The sections of the cell are 
renewed as the boundary surfaces move, so that the 
chloride ion eventually travels through about roo feet 
of gel; 110 or 220 volt lighting circuit is suitable. 
The isotopes, if of different ionic mobilities, will 
appear at opposite end of the sodium chloride gel 
column. It is also suggested that since the discharge 
potentials of the isotopic chloride ions in any naturally 
occurring solution differ by 0-03 volt, it should be 
possible to effect electrolytic fractionation.—J. W. 
Churchman: The mechanism of selective bacterio- 
stasis. Acid fuchsin at 45° C. appears to kill Gram- 
negative organisms, while Gram-positive organisms 
are unaffected ; gentian violet has the reverse effect. 
A mixture of two similar dyes showing this selective 
bacteriostasis may prove fatten for the treatment 
of infection than either alone——H. C. Sherman: 
An investigation of the chemical nature of two 
typical enzymes: pancreatic and malt amylases. 
Malt amylase appears to consist of a coagulable 
otein and a proteose or peptone. Deterioration 
is due to hydrolysis. Pancreatic amylase is similar 
though less stable in solution. With both substances, 
hydrolysis was checked by the addition of amino 
