GS2 
FLORA OF CASHMERE. 
single atom, and occupy (by this;,;and tlie 
preceding proposition) liie same volume; 
hence, the cor. is noanifest. 
Cor. 2. When two tenacious atoms are 
connected chemically, yet so as not to form a 
single condensed group, they will occupy, 
in a gaseous body, tlie same volume as they 
did before the connexion took place. 
For, according to this and the last pioposi- 
lions, they are kept apart by the same force, 
as that by which they were before separated. 
The connecting link will be considered 
afterward^ : such may be called cohesive 
cornhioaiions. 
C'or. 3, A double group will occupy in a 
gaseous body exactly twice the volume of a 
single tenacious atom, or of a single croup. 
For the atom or single group connecting 
two others, as in def. 2, displaces ilie ethe- 
real atoms, and tire parts ofihe atmnspheiules 
between tiiem ; and. because of the given 
pressure, tire same equilibrium will be main- 
tained ; so that the connecting atonr svill per- 
form the effects of the displaced ethereal mat- 
ter, and, tlrerefoie, will not alter the distance 
between the connected atoms; the .same argu- 
ments apply to single groups as to single 
atoms. 
Cor. 4. When gases are mixed, and no 
chemical union, or only cohesive corrrbination 
occurs, the volume is not changed. 
This is manifest from the proposition, since 
an alteration in the absolute force or sphere 
of repirlsion drres not alter the distance between 
the centres of the atoms, so that each .still 
occupies the same volume. 
Iiemc,rk.-~]J zn objection be made to this 
proposiliorr and its cors. by an appeal to f.ct, 
that the .specific gravity of sulphur vapour i.s 
96, that of hydrogen being 1. while the aloirric 
weight of sulphur is only 32; itis easily ob- 
viated ; for there will be perfect agreement, 
if the vapoui- of sulphur consists of single 
groups of two atoms each ; and this is ii.'cely, 
since sulphur has two fusing points, and the 
liquid is less limpid after the second than 
after the first, besides other peculiarities. 
If the atomic weights of phosphorus and 
arsenic be l6 and 38. their vapours are in 
single gioiqts oi four atoms each, probably 
rn tetr.ahedroits, rendering them isoinorpliou.s. 
It is well known that experiment bears out 
these mathernalicai conclusions. 
( To be continued.) 
ILLUSTRATIONS OF THE EOT .-l NY. 
AND OTHER BRANCHES OF THE 
NAIURAL HISTORY OF THE HI- 
MALAYAN MOUNTAINS, AND OF 
THE FLORA OF CASHMERE. 
By J. F, Roylb, Esq., f. l. s,, f. g. s., &c. 
of the H. E, 1. C, Medical Estahlishmerd. 
“ The Convolvidacerz are well known for 
the purgative properties of the roots of many 
of the family, as of Jalap, Scanamony, &c. 
Convolvulus panduratus is substituted in the 
United States for the former; so, in India,/ 
Ipomaa Turpethum, toorhud of the Arabs, 
supposed to be a corruption of the Sanscrit 
trivrif, Hindee nusof, is accounted a power-/ 
ful cathartic, and by Dr. Wallich an excel- 
lent substitute for Jalap, (v. Gordon, in 
Roxb, Fi, ind, ed. Wall. 2, p. 58) ; so the 
seeds of Ipomoea ecerulea. liu^^ool-nil, kala^ 
dana, are accounted purgative in India, as 
are several others of this family, The 
annual shoots not having secreted the due 
proportion of resin, are inert, and even edi- 
ble ; as the stalks of C. edulis and repens. 
The tubers of Batatas edulis, or sweet potato, 
have long been employed as food. 
“ Convolvulus Scammonia^ of which the 
dried resinous juice forms scammony, suk~ 
moonpa,of the Arabs, is chiefly produced near 
Smyrna and Aleppo ; but only inferior kind.s 
find their way to India, though there is little 
doubt that it might be produced of the best 
quality in Northern India. The Jalap ex- 
ported from Vera Cruz was supposed to be 
produced in that neighbourhood, or in that 
of Xalapa, by Macrorhiza ofMichaux. 
But it was known to Humboldt (New Spain, 
vol. iii. p. 36), and also to Dr. Coxe (v. 
Thomson. Elem. of Mat Med. ii. p. 289). to 
be the produce of a different plant. 'I'he lat- 
ter calls it I. Jalapa, and the former says, 
‘ that the true Purga de Xalapa delights only 
in a temperate climate, or rather an almost 
cold one, in shaded valleys, and on the slope 
of mountains.’ The true plant has been fully 
described by Professor Don, in a paper 
read before the Linnean Society, from spe- 
cimens grown from seeds sent by Dr. Schiede^ 
which he procured from Chiconquiera, on the 
eastern declivity of the Mexican .Andes, at 
an elevation of 6,000 feet, Mr. Don retains 
for this the name I. Jalapa, instead of 
Schiedeana Purga, given it by Zuccarini and 
Wenderoth. The discovery of the true loca- 
lity is important, as shewing that the Jalap 
requires a cool climate, and may no doubt 
therefore be cultivated in the Himalayas.” 
Page. 308. 
“ The genus Rheum, or Rhubarb, so 
irnportant in a commercial point of view, is 
more interesting than any other in its geo- 
graphical distribution. R. Rhaponticum is 
found in several parts of Russia on the shores 
of the Bosphorus and of the Caspian Sea, 
eastwards in Siberia, and the lower moun- 
tains of the Altai range: R. Si'^ericum and 
xindulatum of Pallas are considered by Lede- 
hour to be only varieties of this. 11. Leucor- 
hizurn {nanum Sievers) is also found in the 
Altai mountains and the deserts of the 
Kirgliis, Neither of these afford the rhubarb 
of commerce, which is not found within the 
Russian territories, but well known to be 
brought by the Chinese to the Russian 
frontier town of Kiakbta, according to the 
treaty formed between these powers in 1772. 
'i'he Chinese obtain the rhubarb produced in 
China Proper, from that part of Shensee, nOw 
called Kansu, situated betweeen N. lat. 35® 
and But the best, according to the Mis- 
