86 
POPULAR SCIENCE REVIEW. 
The Chemistry of the process of ripening in the Grape . — At the meeting of 
the French Academy on Oct. 4, M. Petit sent in a memoir on the chemical 
phenomena of the process of ripening in the grape. The juice of the green 
grape contains 36 to 37 grammes of acid per litre ; that of the ripe fruit 5 
grammes only ; and these acids have not during the process of ripening be- 
come united to bases — they have actually disappeared. The leaves of the 
vine contain from 13 to 16 grammes of acid per kilogramme ; and, moreover, 
they are richer in acid in proportion as the grape is less ripe and the leaves 
are more green. 
On Orthoxylol . — A very important paper, though one of not much interest 
to the general scientific reader, was lately published in the Report of the 
Gottingen Society of Sciences ( Scientific Opinion , Nov. 10), by Herr Fittig. 
By introducing an atom of methyl into dimethylbenzol the modification of 
trimethylbenzol called pseudo-cumol is obtained. Pseudo-cumol oxidised 
by weak nitric acid yields simultaneously two isomeric monobasic acids 
C 9 H 10 O 2 , which the author has named xylic and paraxylic acids. These two 
acids can only be different because out of the three atoms of methyl con- 
tained in pseudo-cumol, the one changed into carboxyl in the formation of 
xylic acid is quite different from the one changed into carboxyl when para- 
xylic acid is formed. This was shown to be so in this way : By decomposing 
xylic acid by heating it with caustic lime at a relatively low temperature, 
isoxylol is obtained. Paraxylic acid treated in the same way yields a new 
hydrocarbon orthoxylol C 8 H 10 , which differs from isoxylol and from methyl- 
toluol. Paraxylic acid is only decomposed at an extraordinary high tem- 
perature, but the reaction goes on well, and after one rectification the 
distilled carbide is pure. It boils constantly at 140° to 141°, three degrees 
higher than isoxvlol, and possesses an odour quite different from isoxylol or 
methyltoluol and much less agreeable. Unlike the case with isoxylol and 
methyltoluol it is very difficult to obtain stable nitro-compounds from 
orthoxylol by treatment with nitric and sulphuric acids. Dilute hydro- 
chloric acid slowly oxidizes orthoxylol, and gives a volatile acid isomeric 
with toluylic acid. A mixture of chromate of potassium and sulphuric acid 
slowly oxidizes it. 
A neic Ojnum Alkaloid has been obtained in the course of some recent 
researches by Dr. Matthiessen of St. Bartholomew’s Hospital. It is 
obtained from papaverine, and it is, we believe, a very powerful narcotic 
which almost rivals morphia. 
The Chemistry of the Blast-furnace is the title of a good paper by Mr. 
Charles Schinz in the Chemical Neivs of Oct. 29. 
A Test for Albumen . — The following is given by M. Mehu, in the Revue 
hehdomadaire : — Take of crystallised carbolic acid, one part by weight ; 
of commercial acetic acid, the same quantity ; of alcohol, at 90 per cent., two 
parts ; mix, and keep in a bottle. This fluid is intended to detect albumen 
in urine ; and for that purpose, to 100 grms. of this liquid (urine) are added 
2 c.c. of commercial nitric acid, and next, after thorough mixing, 10 c.c. of 
the carbolic acid solution. The reaction is stated to be very superior to the 
use of nitric acid alone. 
What iruiy be obtained from rate Spirits by Distillation. — A very useful 
practical paper on this subject, and one which is highly suggestive to 
