138 
POPULAR SCIENCE NEWS. 
[September, 1S90. 
discovery was made by Dr. Koch at the 
recent Medical Congress at Berlin. He 
stated that he had not only succeeded in con- 
ferring upon guinea-pigs, which are known 
to be peculiarly susceptible to tuberculosis, 
perfect immunity against that disease, but 
had also discovered means of arresting the 
growth and multiplication of tubercle bacilli 
after inoculation. If he should be equally 
successful in preventing and arresting tuber- 
culosis in man, it was not too inuch to hope 
that means would be found for successfully^ 
combating other diseases. If Dr. Koch's 
future investigations confirm the results al- 
ready obtained, his discovery will be of equal 
or even greater importance than that of vacci- 
nation as a protection against small-pox. 
There have, however, been so many alleged 
specifics brought forward lately as a cure or 
preventive for consumption, that we are in- 
clined to wait for furtiier developments before 
forming any opinion as to the value of the 
new method of destruction of the tubercle 
bacilli. 
A RECENT number of the Science News 
(March, 1890) contained an account of some 
peculiar crystalline hailstones which fell in 
Russia. A similar phenomenon recently 
occurred in this country, at Holderness, 
N. II., where, during a severe hailstorm last 
July, many of the stones proved to be sharply 
defined crystals having the form of a double 
hexagonal pyramid, resembling dodecahedral 
quartz, while others were rounded and flat- 
tened, and some had a spherical nucleus with 
small, partially formed crystals projecting 
from it. As the formation of a crystal 
usually occupies a considerable length of 
time, the occurrence of these hailstones only- 
increases the difficulty of suggesting a rational 
theory of the method of their formation. 
THE ALCOHOLS. 
An alcohol may be broadly defined as a 
compound of carbon and hydrogen, in which 
one atom of hydrogen (H) has been replaced 
by the radical hydroxyl ( HO) . Thus common 
alcohol is derived from the hydrocarbon 
ethane (Cjll,i), which may be represented by 
a structural formula as follows : 
H H 
I I 
H— C— C— H 
I I 
H H 
Replacing one H by H-O, we have 
H— C 
H II 
C— O— U 
or CsHsOH 
H H 
Methyl alcohol, or wood-spirit, (CH:jOH), 
is derived from methane, or marsh-gas, (CH4) , 
in a similar manner. Numerous other alco- 
hols have been prepared from the hydro- 
carbons of the marsh-gas series, the one 
best known being amylic alcohol, or fusel 
oil, (CjHiiOH), which is often present 
in distilled liquors, and, when occurring in 
any notable quantity, is a very deleterious 
and unwholesome ingredient. 
The alcohol used in the arts is always 
obtained from glucose by a process of fer- 
mentation, but it has also been made in the 
laboratory by the direct union of its elements, 
thus proving the connection between the so- 
called organic and inorganic bodies, and 
showing that a living plant or animal is not 
necessary for the formation of the first-named 
class, as was formerly supposed. 
A curious property of alcohol is that 
of uniting as a whole with certain crystalline 
bodies, just as water does when in the condi- 
tion of water of crystallization. Calcic chlo- 
ride unites with alcohol in this way, form- 
ing an alcoholatc, with the formula (CaCl») 
4(C.,H„0). 
Each alcohol, by further oxidation, is trans- 
formed into a substance known as an alde- 
hyde, but which is of interest only from* a 
theoretical point of view. Common alcohol, 
for instance, (CjH.-.OH), is converted into 
ethylic aldehyde (CHaCOH) by removing 
two atoms of hydrogen. A still further oxi- 
dation converts the aldehydes into acids, 
many of which are of much importance. 
Ethylic aldehyde, (CHaCOH), for example, 
is easily oxidized into acetic acid, (CH3CO 
OH), which is the acid present in vinegar. 
Butyric acid, from butyl alcohol, is too often 
present in rancid butter ; while the medici«al 
value of valerianic acid is well known. The 
fatty acids used in soap and candle-making 
also belong to this family or series. 
Sulpliur and oxygen are closely related 
chemically, and often replace each other in 
compounds of a similar nature, and so we 
find alcohols in which tlie atom of oxygen is 
replaced by one of sulphur. The best known 
of the.se is mercaptan, (CjHiiSH), correspond- 
ing to common alcohol. It unites directlj- 
with mercuric oxide to form a solid body, 
whence its name ; but its most evident char- 
acteristic is its horrible odor, which renders 
any investigations upon it a form of scientific 
martyrdom . 
Returning to the ba.se of common alcohol, 
ethane, (C^Ho), there would seem to be no 
reason why two atoms of hydrogen might not 
be repUiced by an equal niunber of hydroxyl 
radicals, and we find that such is the case. 
These diatomic alcohols — or glycols, as they 
are called — arc well known, but are rather 
difiicult to prepare, and have no practical 
value. Ethylene glycol (C2H4 [OH],,) cor- 
responds to common alcohol. 
If we replace three hydrogen atoms of the 
original hydrocarbon by hydroxyl, we obtain 
a class of triatomic alcohols, or glycerines. 
Common glycerine is a triatomic propyl alco- 
hol, (C3H5[OH]a), and is the only one of the 
series having any particular value. 
Hexatomic alcohols, containing six hy- 
droxyl radicals, are known, the most familiar 
being the sweet principle of manna, or man- 
nite, (C6H8[OH],i). 
Carbolic acid, or phenol, is really an alco- 
hol, derived from the benzol or aromatic 
series of hydrocarbons ; benzol (dHc) giving 
phenol (CcHr, [OH] ). Like common alco- 
hol, phenol may be oxidized further to an 
aldehyde and an acid, the latter being the 
well-known benzoic acid. 
The hydrogen atom in the hydroxyl can 
also be replaced by other atoms or radicals. 
A most important instance of this is shown 
in the manufacture of ether from alcohol, 
where the hydrogen of the hydroxyl is re- 
placed by another ethyl radical ; thus alcohol 
(C^HjOH) = ether (C.Hs, O, CiH,,) . In the 
commercial manufacture of ether this reaction 
is accomplished by the action of sulphuric 
acid upon alcohol. 
We have given above only a ver^' few 
of the transformations and derivatives of the 
bodies known as alcohols, but thej are suffi- 
cient to show their chemical importance, and 
al.so to give a glimpse at the most difficult 
and complicated subject of organic chemistry. 
We might have spoken, in addition, of the 
primary, secondary, and tertiary alcohols, 
and their normal, iso, and para modifications. 
When we consider that these numerous forms 
are subject to every possible change in tiie 
way of combination, substitution, and adtli- 
tion of other elements and compounds of 
elements, without altering the original radi- 
cal, or skeleton, on which the molecule is 
built up, we can begin to realize what an 
infinite number of combinations of carbon, 
hydrogen, and oxygen are possible, and that 
when we have, apparently, analyzed a body 
into its ultimate elements, we have only just 
begim to comprehend the mystery sinround- 
ing its formation and existence. 
fOrijjin.iI in Popular Science News.\ 
BRIEF STUDIES IN BIOLOGY. 
BY PROF. JAMES H. STOLLER. 
v. 
THE ST.\RFISH. 
It is well known that the ocean is a.s populous 
with living creatures as the land; but few have 
opportunities of acquainting themselves with the 
inhabitants of this great realm. The appearance 
of the starfish, however, is quite familiarly known. 
Everyone who has been at the sea-shore has been 
interested in observing the curious five-fingered 
creatures that cluster at the bottom, just below low- 
tide mark. Those who have not had an opportunity 
of observing them in their native domain have seen 
! specimens in museums or private collections, pre- 
served in alcohol or in a dried state. 
Under the popular name of starfish are included 
many genera and species, differing considerably in 
respect to secondary characters. Tiie common five- 
rayed star, Asterias vulgaris, found everywhere on 
our northern Atlantic coast, is a good type of the 
order. Of this species there are several varieties ; 
