320 Chronicles of Science. . | April, 
wells, cisterns, drain-pipes, &c., where they exist in continual contact 
with a body of water. In drain-pipes the roots of plants usually con- 
sidered to be free from aquatic tendencies, such as rape (brassica), 
sometimes accumulate to a surprising extent. Henrici surmised 
that the roots which most cultivated plants send down deep into the 
soil, even when the soil is by no means porous or inviting, are de- 
signed especially to bring up water from the subsoil for the use of the 
plant. He devised an experiment for the purpose of establishing the 
truth of these views, by planting a young raspberry in a funnel filled 
with garden soil, the neck of the funnel dipping into water from which 
“it was separated by a paper filter. Roots penetrated the soil and the 
filter, and became water-roots, which being ultimately cut away, and 
the plant put into soil and placed in a conservatory it grew vigorously. 
Henrici considers that he has proved that plants extend a portion of 
their roots into the subsoil, chiefly for the purpose of gathering sup- 
plies of water. 
III. CHEMISTRY. 
Cremicat science has made steady progress during the past quarter. 
Not only do the proceedings of the various learned societies 
chronicled in these pages, the Royal, Chemical, and Royal Institution, 
show that our chief workers have not been idle, but the records of 
progress which we are about to give, are also evidence of important 
advancements which find their way to the public through other 
channels than the leading societies. 
Deserving perhaps the foremost place, stand the researches of 
Professor Graham, Master of the Mint, on the Molecular Mobility of 
Gases. The researches of this philosopher on liquid diffusion must 
be fresh in the memory of every chemist, resulting as they did in the 
introduction of a new and most valuable means of analysis into the 
laboratory. The present investigations* prove that the same laws 
which he has already shown to apply to liquids in their passage 
through porous diaphragms, likewise influence gaseous bodies. In 
researches of this character the difficulty has been to find a porous 
body whose structure was sufliciently compact to prevent the pas- 
sage of the gas en masse, but yet to permit its molecules to have 
free movement. ‘Thin plates of compressed black-lead have at last 
been found to possess the desired property, and by employing this 
material as the porous septum in the diffusiometer several remarkable 
results have been obtained. Space will not permit us to give even 
a brief abstract of the whole of this important paper, we will, there- 
fore, content ourselves with drawing attention to one or two of the 
most striking results. The separation of the gases of the atmo- 
sphere by transmission through a porous material has a peculiar 
interest, although from the nearness of the densities of oxygen and 
: reer a Transactions,’ part ii. 1863; and ‘ Philosophical Magazine,’ 
xxv1. 409, 
