May 2, tP92.] 
THE TROPICAL AGRICULTURIST. 
82s 
merate a few of the best specimens derived cliiefly 
from the materials known as alumina and silica. Of 
these the turquois is perhaps the most prominent, 
and certainly one of most popular. The turquoi* 
consists of about two parts alumina, one part phos- 
phoric acid and one part water. The best color is 
a deep sky-blue, though it is found in various shades 
of blue. It is one of the few precious stones which 
are not transparent. The finest specimens come 
from Persia, and inferior specimens from many other 
places. 
The topaz, another favorite jewel of the second 
order, is found in two or three different varieties. 
The original oriental topaz of the ancients, composed 
chiefly of alumina, was of a brilliant yellow color, 
and was very highly esteemed. In these later times 
it has become exceedingly rare, and more valuable 
even than the diamond. Its rarity is so great, indeed, 
that it has practically gone ou.t of the market, and 
the ordinary topaz of modern commerce is something 
entirely different, and much less valuable. It is one 
of the silicates, and is known as the Brazilian topaz, 
from the country of -its origin. Its color is a lovely 
pink, and it is produced by firing. The metal is 
completely covered and encompassed with sand, which 
is then subjected to a very high degree of heat, and 
after the expiration of a certain time it is 
allowed to cool off gradually, and if the process is 
exactly successful the stone is found to have turned 
to a beautiful pink color. The operation, however, 
is a very delicate and difficult one, and many stones, 
in fact the great majority of them, are ruined. The 
heat may have been too great, or not great enough ; 
it may have been applied too long, or not long 
enough ; the cooling process may have been too 
slow, or too quick. In either case the stone is ruined ; 
and probably not more than one-tenth of the opera- 
tions are entirely successful. This makes the Brazilian 
topaz not only beautiful but valuable. 
The zircon, hyacinth, jacinth, or jargoon, as it is 
variously called, is another beautiful member of the 
second class of gema, which is not as widely known 
as it ought to be. It is remarkable as being by far 
the heaviest of the precious stones. Those which 
are called zircons are brown, violet and green ; the 
hyacinths are red, the jacinths yellow, and the jar- 
goons greyish-white and pure white. They are found 
in Ceylon, Germany, France, the United States, and 
many other places. 
The tourmaline is remarkable for its many and 
varied colors and groupings of shades and colors. It 
is composed chiefly of alumina and silica in about 
equal parts. It is found in Brazil, Ceylon, Siberia, 
Moravia, Elba, Sweden, Burmah, the Tyrol, Canada 
and the United States. 
The opal consists of about nine parts silica and one 
Eart water. Its colors vary from chalky-white to 
luish-white, from yellow to red, and kaleidoscopi- 
cally from one to almost any other color. In respect 
to this variability of coloi% and a sort of mysterious 
opacity, the opal is unique among jewels. For some 
absurd reason it acquired unpopularity long ago as 
being "unlucky," but it is now becoming again a 
a favorite of fashion, as it well deserves to be. The 
best opals are found in Hungary and Honduras, but 
the common varieties are found more or less generally 
all over tho world. 
The chrysolite is a beautiful stone of a greenish 
yellow color, composed of silica, magnesia and oxide 
of ix'on. 
One of the best and most useful of the silicates 
is the garnet, composed of silica, alumina, and pro- 
toxido of iron. It isdistribiated extensively all over the 
world in abundance, and is therefore not very 
costly; but it is exceedingly beautiful, rivalling in 
appearance oven tho ruby. Tho predominant color 
is red, but it varies from a brown to almost a violet 
hue. Carbuncle ia a name applied to all garnets 
that are cut with a smooth rounding top. 
Tho moonstone ia a species of feldspar. It ia 
oolorlesa, or only sliglitcd tinted with blue, green, 
yellow and rod, and is beautifully transparent or 
translucent. Tho lustre is vitreous, and a brilliant 
pearly streak of bright light plays in it from side 
to side. This atone haa latterly "boconae very popu- 
lar, and deservedly so. It is found chiefly in Ceylon 
and Switzerland, and occasionally in Bavaria, Green- 
land, Norway and the United States. 
Lapis lazuli, the "sapphire" of the ancienta, ia an 
azure blue, and ia used sometimes for purposes of 
ornamentation in the jewelry line, though more gene- 
rally for works of larger dimensions. 
There remain to be considered hereafter a number 
of gems of the third rank, composed chiefly of quartz. 
SELECT EXTRA -TROPICAL PLANTS 
READILY ELIGIBLE FOR INDUSTR ALCUL- 
TUaS OB NATURALISATION. 
By Baron Ferdinand von Mueller, k.cm.g , &c. (Mel* 
bourne : Printed for the Victorian Government by 0. 
(Troedel & Co.) Price Ss. 
The eiyhth edition of a book, which has been trans- 
lated into German urid Freuoh, adaptel for Indian 
climates, and modified for that of New South Wales, 
needs no recommendation. The mere mentiou of a 
re-ifsuo is all sufficient. A book of this cbaraoter, 
though to a large extent a compilation, is oae which 
demiinds unusaal knowledge and conaummate jadg- 
ment on the part of the compiler. Its great success 
indicates thit these requieitious have been met. 
Indeed, it is a book which should not only form part 
of the library oE every cultivator, but one which should 
be on the shelves of all those in anyway interested in 
ecoQoaiic botauy. As a condensed encyclop;e jia of the 
latter eubjpct, the book, within its prescribed limits, 
h;is a value for a clans of readers as numerous, or more 
so, than those for whom it was more immediately 
destined. Those plants which are of special interest 
or vulue are marked by an asterisk. In all, 2,485 
plants are mentioLed, besides very msny others, of 
which incidental mention only is made. In the 
appendiceF, details are given as to the temperature 
atd rainfall in various parts of the ooknj of Victoria. 
Lists are also supplied of the genera, arranged ac- 
cording to the purposes for which they are used, 
alimentary, textile, couslructivo, medicinal, and so 
on. A systematic index is also provided, in which 
the genera are arranged under their respective 
natural orders. A list of synonyms and a geo- 
graphical index follow, and these are succeeded by 
detailed lists of plants which furnish a crop in one, 
two, three, or more years, as the case may be. 
Plants adapted for very cold or very dry regions are 
separately enumerated, whilst the work ends with an 
index of vernacular names. The mere mention of 
some of the contents of this volume is sufficient to 
justify our remarks as to its utility. But its author 
is not yet satisfied, nor, indeed, would he or could he 
ever be. Accordingly, we find him, while approach- 
ing the eighth decade of his life, hoping not, indeed, 
that he may see "many more editions of this work 
brought up to the newest standard," but that he may 
" perhaps still be able to publish one more edition 
before passing away." To this end he solicits that 
a.ssistance which all who are able will cheerfully give 
to so valiant and indefatigable a worker as Sir 
Ferdinand voq Mueller. — Gardeners' Chronicle. 
[We can personally testify to the great value of 
this oompendious book of referenoe.— Ed. T. Ar\ 
EGG-PLANTS. 
Some time ago, in passing a fruit shop in Regent 
Street, I saw in the window some fruits of tho purple 
Egg-plant, SoUnum Meiongena. Of course, this is 
cloaely allii^d to tho Tomato, but it does not appear 
to have taken the farcy of horticulturista ; yet when 
co ined, it ia one of the nioit delicious of vegetables 
imaginable. 
As there are Apples and Apple", so there are Egg- 
p'aiits and Egg-pU.utg. The white variety is some- 
timos cultiva't'd in India, but it is the least valuable 
as it is rather bitter ; but the purple varit'tios are culti- 
vated in fields everywhere, and much used by the natives 
ftiid Kurojeans. 
