358 
NAT ORE 
[ FEBRUARY 7, 1907 
conditions cats can still pass a concentrated urine, and 
that its amount is not greater than normal. Even after 
the second operation the urine is not excessive in amount 
or notably dilute. Retention of nitrogen always occurred 
after the first operation, and in one animal after the second 
operation also. Analysis, by Schryver’s method, of the 
blood, liver, and muscles showed, by comparison with 
normal animals, a marked increase, not only in the actual 
amount of residual nitrogen in these organs, especially the 
liver, but also in its percentage relatively to the total 
nitrogen. 
December 6, 1906.—‘ On the Transpiration Current in 
Plants.” By Prof. H. H. Dixon, Communicated by 
Prof. J. Joly, F-R-S. 
The adequacy of the theory which attributes the rise of 
water in trees during transpiration to the traction trans- 
mitted downwards in the water columns has been ques- 
tioned by several different investigators. These objections, 
which have been based on an erroneous view as to the 
effect of the presence of undissolved gas in the water-ways 
or of dissolved air in the water itself, have already been 
disposed of. A more recent criticism maintains that the 
resistance offered to the transpiration current by the con- 
ducting tracts of trees is so great that the forces generated 
in the leaves are inadequate to raise the water, and that 
even if these sufficed, air-containing water could not 
transmit the tensions involved, and hence it is imperative 
to assume lifting mechanisms located in the water-ways in 
order to account for the upward movement of water in 
trees. 
In the present paper it is pointed out that the advocates 
of this view have taken up their position, partly owing 
to an overestimate of the velocity of the transpiration 
current, but principally owing to an excessive evaluation of 
the resistance of wood to the flow of water. 
With regard to the methods employed by the critics of 
the cohesion theory to determine the velocity of the 
transpiration current, the author points out that cut 
branches supplied with colour-solutions draw up these solu- 
tions, not only unretarded by the resistance of the lower 
parts of the stem, but actually with the assistance of the 
atmospheric pressure. There is also reason to believe that 
the velocity in the lower parts of the branches, which is 
the velocity observed in these experiments, is greater than 
that in the more distal parts. Hence the observation of 
the rate of the rise of the colour-solution, according to this 
method, tends to give an exaggerated idea of the velocity 
of the water current in intact trees. As to the second 
method employed for estimating the velocity of the current, 
it is shown experimentally that the transpiration of isolated 
branches enclosed in desiccated chambers does not give a 
fair indication of the total amount transpired by all the 
branches of a tree, but again tends to give excessive results. 
This is evident immediately when 
desiccated branch is able to draw on the water store of the 
whole tree. 
The paper also contains the record of numerous experi- 
ments carried out with the view of determining the resist- 
ance offered by the water-conduits of plants to the flow of 
water under various heads, and it is shown that the 
velocity, which is directly proportional to the head, is in 
the case of the yew between 7 cm. and 9 cm. per hour 
when the head is equal to the length of the transmitting 
piece of wood. According to the recent criticism of the 
cohesion theory, to produce such a velocity would require 
a head equal to almost six times the length of the water 
conduits. Hence the objection that to raise the sap in 
trees 150 metres high would require tensions approximating 
to 100 atmospheres, based as it is on this estimate, is 
without foundation. In reality the cohesion theory would 
demand, if, indeed, the excessive velocities before alluded 
to are assumed throughout the water-ways of high trees, 
that osmotic pressures approaching 30 atmospheres should 
be available in the cells of the leaves. Pressures of this 
magnitude have been observed in the leaves of less lofty 
plants. 
The discrepancy between the results of the observers 
quoted and those recorded in the paper are possibly partially 
due to the use of higher pressures by the former, which 
tend to exaggerate the errors due to the inevitable clogging 
NO. 1945, VOL. 75 | 
we consider that the - 
at the cut surfaces. In this connection, a method is de- 
scribed by which this error may be eliminated when deter- 
mining the amount of water transmitted through a cut 
branch. 
In conclusion, it is pointed out that not only is the 
cohesion theory in accordance with the most trustworthy 
observations, but the fact that other theories, both old 
and new, have to assume properties for the water-ways of 
plants, which are either in the highest degree improbable 
according to received scientific views, or are even directly 
negatived by experiment, seems to support the theory by 
a process of exclusion. 
Chemical Society, January 17.—Prof. R. Meldola, F.R.S., 
president, in the chair.—The relation between absorption 
spectra and optical rotatory power, part i., the effect of 
unsaturation and stereoisomerism: A. W. Stewart. A 
close relation is shown to exist between the general absorp- 
tive power of compounds and their molecular rotation, the 
substance having the greater general absorption having also 
the greater molecular rotation.—Organic derivatives of 
silicon, part ii., the synthesis of dl-benzylethylpropylsilicol, 
its sulphonation, and the resolution of the sulphonic deri- 
vative into optically active components: F. S. Kipping. 
dl-Benzylethylpropylsilicol yields with sulphuric acid a mix- 
ture of sulphonic acids of which one has been isolated in 
the form of its ammonium salt. This acid probably has 
the constitution 
SO,H.C,H,.CH,.SiEtPr.O.PrEtSi.CH,.€,H,.SO,H, 
and is the externally compensated compound. The 
d-methylhydrindamine salt can be resolved by crystallising 
fractionally from aqueous methyl alcohol.—The associ- 
ation of phenols in the liquid condition: J. T. Hewitt and 
T. F. Winmiltl. The authors have determined the surface 
energy of several liquids, and find that the association of 
phenols is diminished or entirely inhibited by the presence 
of ortho-substituents. This effect of steric hindrance is also 
seen with the aromatic alcohols—A new mercuric oxy- 
chloride: J. T. Hewitt. On allowing solutions of sodium 
hydroxide and mercuric chloride in sodium chloride to 
diffuse into one another, through a layer of sodium chloride 
solution of intermediate density, dark red crystals having 
the formula Hg,O,Cl, are deposited.—Preparation of 
chromyl dichloride: H. D. Law and F. M. Perkin. 
Chromic acid is dissolved in concentrated hydrochloric 
acid, and sulphuric acid added in small quantities. The 
chromyl dichloride formed is drawn off and purified by 
aspirating dry air through it and subsequent distillation.— 
Oxidation of hydrocarbons of the benzene series: H. D. 
Law and F. M. Perkin. The hydrocarbons investigated 
were toluene, the three xylenes, mesitylene, y-cumene, and 
cymene. In all cases varying yields of the monoaldehydes 
were obtained.—The constitution of silver nitrite; a correc- 
tion: E. Divers.—Aromatic selenonium bases: S. Smiles 
and T. PP. Hilditch. Trianisyl- and __ triphenetyl- 
selenonium chlorides and some of their derivatives are de- 
scribed.—The relation of colour and fluorescence to con- 
stitution: A. G. Green. A study of the phthaleins of 
phenol and quinol, which the author has had in progress 
for some time past, has brought to light several facts 
strongly confirming the view that the coloured salts of 
these phthaleins have a quinonoid structure, thus render- 
ing Silberrad’s deductions as to the structure of these bodies 
unnecessary (Journ. Chem. Soc., 1906, Ixxxvii., 1787).— 
Tetraketopiperazine: A. T. de Mouilpied and A. Rule. 
—Transformations of highly substituted nitroamino- 
benzenes, ii., s-tribromo-l-nitroaminobenzene: Miss A. E. 
Smith and K. J. P. Orton.—Resolution of tetrahydro-p- 
toluquinaldine into its optically active components: T. C. 
Beck and W. J. Pope. By treating two equivalents of 
dl-tetrahydro-p-toluquinaldine hydrochloride with one equi- 
valent of the ammonium salt of Armstrong and Lowry’s 
d-aB-bromocamphorsulphonie acid under appropriate con- 
ditions, a nearly quantitative separation of d-tetrahydro-p- 
toluquinaldine-d-a8-bromocamphorsulphonate is obtained.— 
Note on the theory of valency: W. Barlow and W. J. 
Pope. A reply to Chapman (Proc. Chem. Soc., 1906, 
xxii., 320).—The condensation products of triacetic lac- 
tone with acetoacetic ester and B-aminocrotonic ester : 
F. N. A. Fleisechmann.—Derivatives of multivalent iodine, 
part ii., action of heat on p-iodoacetophenone dichloride, 
