June 29,1872.] 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
1019 
posit.] It may be remarked that it is more than 
usually difficult to remove from valerianate of zinc 
the whole of the sulphate; and all commercial samples 
give a precipitate with chloride of barium. With 
regard to the last test, it is intended to detect ad¬ 
mixture of butyrate of zinc, a sophistication which at 
one time was not uncommon. 
Zinc uu. 
[§ Zinc of Commerce.] 
The principal ores of zinc are blende, ZnS, cala¬ 
mine ZnC0 3 , and the red oxide. To obtain zinc 
the ore is first roasted, by which, in any case, it is 
converted into the oxide, and it is then heated with 
coke or charcoal in earthen or iron retorts of peculiar 
shape. The zinc distils over and condenses in the 
liquid form. Commercial zinc containsTead, iron, and 
generally traces of cadmium and arsenic. To obtain 
it free from impurity, the carbonate may first be pre¬ 
pared and this, after conversion into oxide, distilled 
with pure charcoal. 
Zinc for chemical purposes is generally granulated 
by melting it and pouring in a thin stream into a 
quantity of cold water. 
Ordinary zinc is somewhat brittle at common 
temperatures, but becomes malleable, and may be 
rolled into sheets when heated to 250°-300° F. 
When the temperature is further raised to a little 
over 400°, it becomes so brittle that it may be rubbed 
to powder. Although ordinary zinc dissolves in dilute 
acids very readily, this is not the case with the pure 
metal. The particles of lead which are imbedded in 
common zinc, form with the zinc in presence of the acid 
a voltaic combination in which the zinc acts the part 
of the positive metal, and the lead the negative. To 
make pure zinc or tin dissolve readily in acids, it is 
best to place in contact with it a piece of platinum 
foil; the same kind of electrical polarization is then 
set up, and this very greatly assists the chemical 
action. 
MATERIA MEDICA NOTES. 
BY JAMES COLLINS, F.B.S.E. 
Curator of the Pharmaceutical Society's Museum. 
Gum Euphorbium. —Dr. E. Cosson, in an interesting- 
note on Euphorbia resinifera, Berg-, read before the Royal 
Botanical Society of Belgium, verifies the statement of 
Berg, that the Gum Euphorbium of commerce belongs to 
the species to which Berg gave the name of E. resinifera. 
Dr. Cosson found in Yon Martius’ collection at Brussels, 
a specimen of Gum Euphorbium with sufficient of the 
dried stems of the plant producing it to give a good idea 
of the plant. Probably Yon Martius received these 
specimens from his brother, Dr. T. W. C. Martius. 
The history of this acrid gum is very interesting. E. 
canariensis , L., E. ojfcinarum, L., E. antiquorum , L., and 
E. tetragona , Haw., have each been accredited with its 
production ; but Dr. Pereira, who examined the question 
w-ith his usual critical ability, stated that only E. cana¬ 
riensis fulfilled all the requisite conditions of locality, 
etc.; and that he felt little hesitation in ascribing the 
gum to this plant. He says (Elements Mat. Med. vol. 
ii. pt. 1. p. 399, 1855) that the specific characters ‘‘apply 
to the branches found mixed with the Euphorbium of 
commerce. They agree w r ith the description and figure 
of Tithymalus aizoicks lactif mis , the Euphorbia canariensis 
of Plunkenet.” Miller also (Gard. Diet. vol. i. art. 
Euphorbium) states that in looking over some Euphorbium 
in a shop, he “ found several spines amongst it, which 
exactly agreed with those of that plant.” Pereira found 
in some specimens of the gum, spine3 resembling those 
of E. tetragona , Haw. 
But better materials led Berg to trace its origin to a 
new species, to which he gave the name of E. resinifera, 
and described from dried remains picked out of the gum. 
E. resinifera has astern one-third the size of that of E. cana¬ 
riensis, and stalked umbels, whilst E. canariensis has al¬ 
most sessile flowers. Berg gives figures in ‘ Berg und 
Schmidt, Darstellung und Beschreibung sammtlicher in 
der Pharmacopoeia Borussica.’ The gum contains 20 per 
cent, of an acrid principle Euphorbin ((YgHwO^, so acrid 
indeed that in the collection of the gum the fingers be¬ 
come excoriated if brought into contact with it, and it is 
the practice to cover the mouth and nostrils to avoid the 
excessive sneezing which would otherwise ensue. The 
best general account of the production of this gum is that 
of Jackson, in his ‘ Account of Morocco.’ 
Dr. Cosson has also compared the various materials ho 
has with a growing plant at Kew (which has not yet 
flowered), sent by Mr. F. Cartensen, the English Consul 
at Mogadore. If the history of this plant can be satis¬ 
factorily attested as being the species actually producing 
the gum, its flowering will be looked to wnth some degree 
of interest, as the question can then be set completely at 
rest. 
Cinchona Rosulenta. —Mr. Howard has recently 
cleared up another doubtful point in the cinchona ques¬ 
tion. He has described and figured in the ‘ Bulletin do 
la Societe Botanique de France’ a new species, named 
Cinchona rosulenta, a native of Ocana, in New Granada. 
The vernacular name appended to the specimens of this 
plant, which were collected by Purdie in October, 1845, 
is “ Quina de la tierra fria.” C. rosulenta is very close, 
both in appearance and chemical composition, to C. 
succirubra ; the bark, however, has a more roseate hue, 
and the leaves approach C. ovata, the nerves, however, 
being more rigid and prominent. Mr. Howard identifies 
this species with the Quinquina rose d'Ocana, of M. 
Delondre, a figure of which is given in that author’s 
‘ Quinologiealso with M. Rampon’s Quinquina a 
quinidine , described in Dr. Planchon’s ‘ Des Quinquinas 
and also with Dr. Wittstein’s ‘ Peseudo regia ' 
This bark has long been known in French commerce 
under the name of “ Quina rose,” and we are grateful to 
Mr. Howard for thus clearly settling its synonymy, and 
giving it a botanical position.— Journal of Botany. 
PURIFICATION OF WATER CONTAINING ORGANIC 
IMPURITIES. 
by prof. g. dragendorff (Dorpat, Russia). 
Years ago, as is well known, Scherer proposed for the 
purification of water, especially when it contained large 
quantities of organic substances, the use of a solution of 
a ferric salt, especially of the sulphate. 
Lately, Gunning made a similar proposition, recom¬ 
mending ferric chloride for this purpose. The object is 
plainly the precipitation from the ferric salt of the ferric 
oxide, which carries with it organic compounds, as for in¬ 
stance the deposits of many mineral springs which sepa¬ 
rate from the water all, or almost all, organic impurities. 
There the action is mainly one of surface attraction of 
the hydrated oxide in solution, which is greater with the 
increased volume of the precipitate. 
This attraction first acts only upon the substances in 
solution, but extends to a large portion of the suspended 
substances, vibriones, amoeba?, etc. The precipitate acts 
upon them like the coagulation of albumen in solution, 
which at the moment of coagulation envelopes suspended 
particles, that render the liquid turbid. That the freed 
acid at the same time changes ammonia, its carbonate, 
and similar substances present in such water, into loss 
volatile compounds, removing thus ammonia compounds 
in case of distillation from the distillate, is a matter of 
course. But even the acid may in part remain free,, and 
especially,- if carbonates do not abound, be injurious. 
At least, if the liquid becomes concentrated during sub- 
