26 
POPULAR SOlEN^CE NEWS. 
[February, 1891. 
rubies originally produced by the Fieiich chemists 
were made by heating to re(]ness onlinary alumina 
containing a little bithi-omate of potash w ith cer- 
tain fluorides, particularly fluoride of barium. 
The only difference in their latest mode of pro- 
cedure is that the mixture rendered allialine with 
potassium bicarbonate, and the mingling of the 
components purposely left imperfect so that the 
combination should take place between the vola- 
tilized elements, and the crystals could grow by 
.5>%1^^V\ 
Fig. 1. 
" feeding,'" as is done with crystals by the wet 
process. Another difference is in the manipula- 
tion. Instead of using a gas furnace, they were 
enabled, through the courtesy of MM. Appert, the 
glass manufacturers, to l<eep large crucibles con- 
stantly heated for one weeli at a temperature of 
2,400° F. In this manner batches of six pounds 
were obtained out of ten-pound charges. 
Flg.p. 
After the process is completed, the rubies are 
found adhering to the sides of the crucible (Fig. 
2) in a crust of gangue nearly one inch thick, from 
which they can be readily removed by simple rub- 
bing. Tlie largest rubies thus far obtained weigh 
75 milligrammes — about one and a quarter grains, 
or one-third of a karat. Their crystalline form, 
hardness, and physical characteristics were in 
every way identical with the natural stones. 
As is well known, the sapphire is chemically the 
same stone as the ruby, only differing from it by 
its bi-illiant blue tint, which has heretofore been 
supposed to be due to a trace of cobalt, copper, or 
some other metallic oxide giving that color. It 
was found, howevei', in these experiments, that 
blue rubies, or sappliires,- were produced in the 
same crucible as the red ones, although in much 
smaller numbers; and in one case a crystal was 
red on one side and blue on the other. It is thus 
probable that the ruby and sapphire both owe 
their brilliant colors to the same metals- — possibly 
chromium in different stages of oxidation. 
'I'he accompanying illustrations are reproduced 
from La Nature. 
AX EXTRAORDINARY PROJECT. 
TiiK success of the Eiffel Tower at the recent 
Palis Exposition has developed a craze for novel 
and audacious engineering feats, with the idea of 
eclipsing that remarkable structure. The latest 
project in this direction is that of a French engi- 
neer, M. (iAiiuON, who proposes to build a conical- 
shaped carriage, sufficiently large to contain fifteen 
(jeisons, and, iiaving erected a tower one thousand 
or more feet in height, to allow- the carriage to 
drop from the top into a funnel-shaped reservoir 
of water, whicli, it is expected, will bring the car- 
riage slowly to rest without shock or damage to 
itself or its passengers. 
Fig. 1. 
A heavy body falling from a height of a thou- 
sand feet would attain a velocity of over two hun- 
dred feet per second before reaching the ground. 
This is much more than twice as fast as the swift- 
est railroad train. The details of M. Garron's 
scheme are shown in the illustrations. Tlie cone- 
shaped carriage is shown in Fig. 1. The passen- 
ger compartment is in the upper portion (Fig. 2), 
while the lower part is composed of a nest of 
concentric steel cones, which are intended to 
strengthen the carriage and prevent any undue 
compression of the air in the interior when it is 
forced into tlie well beneath the water. The pas- 
sengers are comfortably seated in easy chairs, 
and, according to the author of the scheme, " the 
rapid vertical fall will be a source of physiological 
emotions which, with many persons, will be very 
vividly appreciated." 
It is claimed that the mathematical conditions 
governing the fall of such a carriage from a great 
height have been carefully worked out, and that 
the project is a perfectly safe and practical one, 
worthy the attention of the managers of the com- 
ing exhibition at Chicago. We are afraid, how- 
ever, that even the oflfer of a free pass over this 
aerial road would not tempt many persons to 
undertake the journey, unless a few of those 
cranks who delight in risking their worthless 
Fig. i. 
lives might be induced to make a "trial trip." It 
would probably not be any more dangerous than 
going through the Niagara rapids in a barrel, as 
several persons have safely done ; but the possi- 
bilities of the carri.age failing to drop directly into 
the well are too great to ever make the project a 
popular one, and we are of the opinion that the 
scheme will not be practically realized until 
another century at least. 
.Assuming that the idea could be practically car- 
ried out, it is an interesting question what would 
be the effect produced upon the passengers in the 
car. When riding at night over a smooth railroad 
one is often almost unconscious of the motion, and 
aeronauts say that they have absolutely no per- 
ception of the motion of the balloon. It is most 
probable that the fifteen passengers shut up iA 
Garron's car, with no communication with the 
outside light or air, would be entirely unconscious 
of the journey, and would have no "physiological 
emotions " whatever, beyond a slight shock at the 
commencement of the journey and — let us hope — 
a not much more violent one at its aqueous ter- 
mination. 
[Special Correspondence of Popular Science News.] 
PARLS LETTER. 
The Koch method for the treatment of tubercu- 
losis is, as might be expected, the topic of the 
moment. If some journalists of the extra-radical 
and extra-silly type — -such are always to be found 
— are excepted, it must be recognized that the 
whole scientific press and the larger part of the 
daily one, all serious organs included, have hailed 
Koch's discovery with the utmost satisfaction. 
