June i, 1891.] 
THE TROPICAL AGRICULTURIST. 
841 
But there is a possibility, even a probability, that 
some day the problem may be solved in the simplest 
fashion, and then tbe standard of value, whicla the 
alchemists in vain tiieJ to alter, must be sought else- 
where than in stones no longer precious. Fow people 
will care to pay high prices for the sentimental pleasure 
of wearing “ real ” gems, while the artificial oi es 
cannot be distinguished from them hy any tests less 
exact than those of the chemist. — Loudon Standard. 
Artificial Rubies. — The experiments of uIM. Ptciny 
and Vernenil on the ariticial production of rubies have 
been in progress for some years, but it appears, from 
their recent communication lothe Gom^des-lieudus, that 
they have now successfully overcome the difficulties 
which attend their manufacture, and are obtainiug 
much larger crystals. The artificial rubies have already 
been employed as pivots in watches, and are said not to 
be inferior to the natural s' ones in hardness. Tbe pro- 
cess consists in heating alumina and a trace of potas- 
sium bichromate with barium fluoride oi a mixture of 
fluorides of the alkaline earths to a high temperature 
for several d.iy.s. Recent progress has been due to the 
discovery that the addition of a small quiutity of potas- 
aium carbonate to the mi.xture, so as to reuder the 
fused mass alkaline, facilitates the formation of the 
crystals. It is believed that the crystals are prolnoed 
directly from the interaction of the volatile oompoiuuls 
produced, and, by employing crucibles of several litres 
capacity in gas furuaces as much as 3 kilo.s. of rubies 
are obtaiued iu a single operation. — Industries. 
ARTIFIOAL RUBIB9. 
To THE Editor of the '• Standard.” 
Sir, — I have read with interest your article in 'Ihe Stan- 
dard eflast Saturday on the manufactured rabies pro- 
duced by MM, Premy and Verneuil. The general buying 
public may no doubt be somewhat frightened at the 
thought that instead of the natural gem they may only 
get at best au imitation. The generality of buyers of 
precious stones are usually good juiiges, and not likely 
to buy anything hut the real article. In the imitation, 
or lather manufactured, ruby, it is noticeable that all 
the spots and flaws run into one corner, like the tail of 
a comet, while in the genuine article spots and fl-.ws, 
&c., are diffused over the stone ; and another thing is 
that in no imitation of diaraouds, pearls, rubies, and 
emeralds can there bo found the hardness possessed by 
nature’s own gems. 
With regal d to the dimond manufactured by Mr. 
Hannay some years ago, may' I add the whilst being ex- 
hibited at the Royal Society, I asked Mr. Ilanuay as to 
how the stone would act when placed on tbe diamond 
wheel to cut it into shape. Ho informed me that it 
would, at the first revolving of the wheel, crumble to 
powder; it is impossible to manufacture the hardness 
necessary. May I ask you to kindly find space for this, 
60 as to reassure those who own, or contemplate being 
possessors ot, these gems. 
I am, Bir your obedient servant. 
EDWIN ^y. STREETER, 
Bond-street, London, W. , March 16th. 
THE SILVER MARILET AND EXCHANGE 
IN 1890. 
Even at this late period it may be worth while 
to call attention to the facts revealed by a diagram 
showing the prices obtained for bar silver in Lon- 
don and the rate of exchange in Colombo for demand 
bank bills on London during 1890. Beginning with 
bar silver, it was at Hd. when the year opened and 
the lowest point it touched in its progress through 
the months was 431- in February while the highest 
was 54A in August. The variations ranged from 
^ to 24, and at tho oloso of the year thu price 
stood at 48 — fourpenco better than at the start. 
In January 444 was what was generally ob- 
tained, but in February there was a depression of 
about a penny. This however was slightly improved 
upon in the succeeding month. On 4th April 
the price was 43| and from this it went on 
advancing a farthing in one week, twopence 
in the next and other twopence in the third 
week. From 48 it fell away , however, to 40 in 
the beginning of May. In the course of that 
month it made an effort to get up again and 
was so far successful, 47i being realized, but 
it was not able to keep this up and fell to 46;^ 
June coming to its assistance, lifted it till 
it was within reach of 49, but again there was 
a fall and it came down to 47|. From this it 
made an attempt to rise almost immediately to 
i s former altitude but the effort was too much 
for it and after just touching 48^ it sank down 
to 47|. In July there was better fortune and 
between the second and third weeks 50 was re- 
gistered. In the fourth week J had to come off, 
but this was merely a temporary reduction, and 
when August opened the figures— thanks to 
American legislation — were 51^ At first there 
seemed to be some uncertainty as to whether 
tho price would go beyond this, but in the 
second week this was placed beyond doubt. 
After one or two short leaps it bounded to tho 
height of 5-4J from 51J in one week, in a day 
or two it fell back a hut rebounded and wlien 
the month closed had attained 54-J-. It had taken 
about five months to reach this pinnacle, but it was 
not allowed to remain more than a few days there. 
On Sept. 5lh it had dropped to 64 and in the 
following week to 53. In tho next week it slightly 
recovered itself, but from 53J on 19 th Sept, it 
fell away to olj on the 26th. Iu the course of the 
succeeding week it touched 60, rose to 51^ and 
again sank to 50 from which it had not risen 
more than | when it was once more thrown down 
and continued its descent with occasional inter- 
ruptions till the middle of November when it was 
as low as 45. An improvement now set in, and 
at one bound the price went up 2J, and at another 
I2- In the beginning of Heoember there was a 
sudden drop from 48J to 47i. An advance was 
made upon this in a few days, but another fall 
occurred which brought down the price to 474. 
From this it went up again at one bound to 
49i, but came down to its former level in the course 
of a week. The year closed, however, by showing 
4 of an increase. 
Turning now to the rate of exchange it 
started at Is 54 and the lowest point it 
touched for demand bills on London, during 
the year was Is 4|d in the middle of Feb. 
while the highest was Is 8Jd in the end of Aug. ; 
At the oloso of 1890 it had just touched Is 64d.’ 
Opening at Is 6d the ra'e rose in a couple of 
weeks to Is 5§J, but this level was not long 
maintained, ana in the third week of February it 
had touched Is 4:^-4. From this point there was a 
gradual improvement till the beginning of May 
when the variations became more frequent but 
generally in an upward direction. From Is 5jd 
in the first week of the month it jumped to Is fid 
between tho 16(h and 23rd. It was down at Is 
5^1 at the end of May, but in the second week 
of the next month it had put on a penny. This 
however, was _ taken off before the month ended 
aud only p.anially recovered when July opened. 
At this time the rate was Is C^d and it rose 
rapidly to Is 7.^4, Is 74d and so on till 
the 22nd August when the top point was 
reached. Between 22nd Aug. aud 5'.h 8ept. there 
were several changes, the variation being from about 
1,84 to I/8.J ami up again. In September tlie 
tendency was most decidedly downwards aud from 
1/8J on the 5 li it oauio down to l.fi^' on the 2fith. 
In the begiuiug of October there was a sudden ries 
