January 7, 1899, 
THE GARDENING WORLD 
301 
ARDENING JgiSCELLANY. 
DRYOPTERIS ACROSTICHOIDES. 
This pretty Dryopteris is one of the most striking of 
Canadian Ferns. The fronds are dark green and 
glossy, and keep their colour well through the winter. 
This fact has caused the popular names of Evergreen 
Rock Fern, and Christmas Fern to be applied to it. 
The pinnae are shaped like a scythe, the margins 
being characterised by a row of fine silvery hairs, 
whilst the apices develop into a bristle. The sori 
are to be found only on a few of the pinnae near the 
top of the fertile fronds. The sori run together and 
cover the pinnae as with a mass of brown felt. The 
fruiting fronds are taller and more erect than the 
barren ones. The plant best loves rocky wood, and 
it is in such places that it is to be found. It is rare 
in the neighbourhood of Montreal, being found only 
in one confined space above Ravenscrag, but in 
Eastern Ontario there are quantities of it, and it is 
also abundant in the adjoining State of New York. 
There is a variety of the type known as the Scalloped 
Christmas Fern, differing in having the lobes of the 
pinnae cut; in habit and everything else it is the same. 
The variety is rather more rare than the species, 
but both are occasionally found in the same neigh¬ 
bourhood. 
THE HARDY PASSION FLOWER. 
Were it not for the uncertainty of our climate, this 
would in all probability be the most popular among 
all our climbers for decorating the front of our 
dwellings, verandahs, &c„ but unfortunately we are 
liable to spells of frost which sometimes kill it out¬ 
right ; the growth and foliage are everything which 
can be desired, and the flowers most beautiful, and 
if only it fruited as freely at all times as it is doing at 
places this season it could justly be claimed for it 
that it stands in the front rank as a berry-bearing 
plant. I passed a front porch the other day on 
which it was fruiting splendidly—truly a most beau¬ 
tiful sight, of which the owners might justly feel 
proud.— W. B. G. 
ILEX CORNUTA. 
The Japanese or horned Holly is not a well-known 
plant, but its merits are unquestionable. In consti¬ 
tution it is nearly, or quite, as hardy as our native 
species, I. Aquifolium, and it is quite distinct in 
appearance. One good quality which specially 
characterises it is the freedom with which it berries. 
On this account alone it is worthy of being planted, 
for our British Holly does not always berry well. 
The leaves are very tough in texture, and have three 
very strong spines towards the apex, which spines 
often develop to such an extent as to resemble horns, 
hence the specific name of " cornuta." The berries 
are much larger than those of I. Aquifolium, and 
the plant is a more vigorous grower. 
NEMESIA STRUMOSA NANA COMPACTA 
GRANDIFLORA. 
This handsome plant, with the unbearably long 
name, or rather list of names, appears in the list of 
novelties for 1899 sent out by the celebrated French 
house, Messrs. Vilmorin-Andrieux & Cie. As one of 
the varietal names signifies, this is a dwarf strain. 
The flowers are relatively large, and comprise 
several shades of rose, orange, and purple. If cut 
back in August after the first flowering is over the 
plants commence to flower a second time, and they 
keep this up until frost steps in and puts its veto 
upon their further production. This dwarf, com¬ 
pact, large-flowered Nemesia is recommended both 
as an edging plant for flower beds and for culture in 
pots. 
VIOLET LA FRANCE. 
In the list of novelties for 1899 sent out by Messrs. 
Vilmorin-Andrieux & Cie., 4, Quai de la Megisserie, 
Paris, Violet la France occupies a prominent position. 
Judging from the illustration of it given, the plant is 
of very dwarf and compact habit, and also remarkably 
free-flowering. The flowers are described as being 
exquisitely sweet-scented, purplish-blue in colour, 
with a metallic reflex, and the petals as of extra¬ 
ordinary size and well rounded. The stalks are said 
to be long, substantial, and erect, raising the flowers 
well above the foliage. The variety is recommended 
both for cultivation out-of-doors and under glass. 
This novelty has therefore all the qualities that go to 
make up a good Violet, and should thus not lack 
friends on this side of the silver streak. 
BLUE HYDRANGEAS FOR ALL. 
Everyone knows and admires the blue Hydrangea, 
but what is not so well known is the method of 
obtaining these blue flowers, so they continue to be 
rare and much sought after. Thus M. Ernest Bar, 
in the issue of the Nord Horticole for December, ex¬ 
presses himself. He goes on to remark upon the 
mixtures that have been tried and recommended, 
such as soil from slate quarries, pounded slates, 
feriugineous soil, sulphate of iron, etc.,—a lot of 
materials that most people have not close to hand, 
and which they cannot easily procure. The method 
recommended by M. Bar is, on the other hand, ex¬ 
ceedingly simple, the necessary materials for the 
compost being within the reach of everyone. It 
consists simply in the employment of ordinary coal 
ashes. The compost he recommends, and which he 
used first some five years ago, consists of one-third 
peat, one-third of well decayed manure from an old 
hot-bed, and one-third of coal ashes. In this com¬ 
post he avers that he has always been successful in 
procuring Hydrangeas with flov'ers of the purest 
blue for which one could wish. If this, indeed, be 
so there will be many British horticulturists who 
will be grateful to M. Bar for his generosity in thus 
making his secret known to the world. 
-< 4 —-- 
METHODS OF PREPARING RUBBER. 
So much has been written within the last few years 
on the subject of indiarubber, the sources of our 
supply, and the possibility of acclimatising the best- 
yielding trees in our colonies, that at first sight it 
may appear that there is little more to be said. A 
study of the methods in use for preparing rubber 
from the latex, or milk, may, however, be of use to 
many interested in the formation of plantations, 
especially if some attention is paid at the same time 
to the inaccurate statements made in some recent 
publications, which apparently have disregarded the 
valuable series of papers on the subject contained in 
our one journal devoted to economic botany, the 
Kew Bulletin. 
The methods in use at present are either the out¬ 
come of the limited experience of uncivilised peoples, 
or the application of experiments made without pay¬ 
ing due attention to what is known of the chemical 
constitution and physical properties of latex. As a 
good example of the latter, we may take the experi¬ 
ments of Morisse, who found that coagulation was 
brought about in the latex of Hevea by the addition 
of alcohol, phenol, hydrochloric acid, nitric acid, 
sulphuric acid, calcium chloride, ferric chloride, cor¬ 
rosive sublimate, &c. As the outcome of these 
experiments, a mixture of phenol in alcoholic solu- 
lution, and dilute sulphuric acid, was recommended 
as a coagulating agent. 
The latex is, as a general rule, a thick, white fluid, 
composed of small particles of rubber in suspension 
in a clear watery solution of various substances. 
Unfortunately, only the latex of a few trees has, as 
yet, been chemically examined when fresh. 
The analysis of the latex of Hevea brasiliensis 
shows that it contains :—■ 
Rubber. 32 per cent 
Proteid matter. 2 3 „ 
Calcium and sodium salts 9 7 ,, 
Resin. traces 
Water . 55 to 56 ,. 
It is slightly alkaline to litmus paper. 
The presence of albumin, globulin, and other pro- 
teids, has been demonstrated by Green in some 
other rubber-yielding latices. 
As a general rule all these substances are to be 
found in rubber as it is at present prepared, often 
with others added to bring about coagulation of the 
latex, and accidentally or intentionally added im¬ 
purities,such as bark and clay. In all cases the per¬ 
centage of impurities is large, how large we shall see 
later, and when it is remembered that some cause a 
rapid deterioration of the rubber it is obviously 
much to the interest of those connected with the 
industry that a method of preparation should be 
adopted which would minimise them or ensure their 
absence. 
I propose now to consider a few of the better- 
known varieties of rubber. 
Para Rubber is the product of Hevea brasiliensis, 
a tree which thrives in many parts of the Amazon 
valley, British Guiana, &c. As pointed out by 
Churchill in his consular report, there is no danger 
of this source of supply becoming exhausted, though 
this is the frequent cry of companies formed for 
rubber-planting, usually fated for an ephemeral ex¬ 
istence. The tapping is done with considerable care 
by the natives, and even should a district become 
exhausted, in a few years a fresh supply of trees 
springs up. From the planters’ point of view Brazil 
is hardly a suitable couutry, for the climate is bad, 
it is difficult to obtain labour, and the exchange is 
liable to endless variations. The trees have, how¬ 
ever, been introduced into Ceylon, where small 
plantations exist, and into other colonies. 
The method of preparing the rubber has been so 
frequently described that repetition is needless ; but 
a “ translation of a valuable article on rubber of the 
Orinoco " has received so much attention of late that 
it requires some examination. One of its most 
striking errors is the following : “As the juice con¬ 
tains a considerable quantity of water, the prepara¬ 
tion of rubber consists essentially in separating the 
former from the latter, which is performed by 
evaporating the wa'er by means of a heating process 
or obtaining its coagulation by certain chemical pro¬ 
cesses. Although the last system is more rapid they 
prefer the former, as they pretend that the rubber 
thus obtained is of a superior quality—a supposition 
devoid of all reason." 
As I have already had occasion to show, this 
statement is incorrect, for the heating continues for 
too short a time; (" the rubber’’ is not “dried in a 
few minutes ’’) to evaporate off some 50 per cent, of 
water, and further there is no loss of weight until the 
clot begins to contract and squeeze out water. 
Neither is “ the supposition devoid of all reason,’’ 
for it is a well-known fact that the smoked rubber is 
far preferable to that obtained by chemical pro¬ 
cesses. A comparison of the prices of “ Para fine " 
and " sernamby ” should be sufficent proof of this. 
Why it is so may be made clearer from the following 
experiment. At the end of a day’s work I had 
several litres of latex left, to which an equal volume 
of water had been added, which would not keep over 
night without coagulating. To this a small quantity 
of acetic acid was added, and in a short time the 
whole of it had formed a stiff curd. On pressing 
and drying, a portion of the water exuded from this 
mass of sernamby, but it still remained full of 
cavities, and the proteid matter in it quickly decom¬ 
posed,so that ultimately a stinking,inflated mass was 
obtained, 
If this latex had been coagulated by smoking it 
would have yielded a wet rubber, but the subsequent 
decomposition of proteids would not have set in, for 
the creosote contained in the smoke would have 
acted as an antiseptic and prevented decomposition, 
as it does when meat is preserved by smoking. 
Then again we find, " the rubber thus prepared 
(by smoking) acquires a darkish colour, due to the 
particles of coal which adhere to the outer skin. 
Some people believe that this tends to improve it, 
but such is not the case, for it is thus impregnated 
with impurity.” Now when these “bottles” of 
rubber are cut across, the fresh, laminated surfaces 
are a silvery-grey colour, and as each layer is ex¬ 
posed to the same extent to the action of the smoke 
it is difficult to account for the outer layers only 
•being so coloured. The freshly cut surfaces, how¬ 
ever, soon darken and become black in turn, so that 
the explanation of oxidation seems fai more probable, 
especially when taken in conjunction with the fact 
that the smoke is white and not black, for the nuts 
are simply dry-distilled and not actually burnt. If 
the smoke of these heated urucuri nuts is condensed 
it forms two layers of liquid in the receiver, one a 
clear limpid solution consisting mainly of acetic acid, 
the other, darker in colour, of creosote. 
The hot vapour of acetic acid brings about the 
coagulation of the proteids of the latex-, as may easily 
be proved by direct experiment. 
A solution of alum is said to be in use for prepar¬ 
ing rubber in some parts of the Amazon Galley. 
Morisse states that alum solution has no effect upon 
the latex of Hevea species, however. 
The loss in the factories on making up Para 
rubber is as follows:—(1) Para fine, 10 to 15 per 
cent.; (2) Entre-fine, the carelessly smoked pieces, 15 
to 20 per cent. ; (3) sernamby, rubber pulled from 
the cuts on the tree and cups, coagulated by being 
