90 
POPULAR SCIENCE REVIEW. 
fur prakt. Chemie ” (No. 13, 1870). — Dissolve, lie says, 1 decigrm. of very 
pure permanganate of potassa, and 1 grm. of perfectly pure soda (prepared 
from sodium) in half a litre of distilled water ; there is thus obtained a per- 
fectly red-coloured liquid, which, upon the addition even of a very minute 
trace of any hyposulphite, becomes, at once, green. This test, the author 
states, is so delicate, that traces of a hyposulphite present in neutral sul- 
phites may thus be detected. 
Loss of Weight in Platinum, Crucibles. — In “ Dingler’s Journal” for October, 
which is considerably abstracted in the u Chemical News,” Dr. F. Stolba is 
stated to have made a number of experiments on this subject, the results 
being that the rougher and more unpolished the surfaces of platinum 
crucibles are, the more readily they are acted upon by the flame of well- 
made Bunsen-burners, because the rough unpolished surface promotes the 
formation of a compound of carbon and platinum, which is partly consumed 
by the flame, partly mechanically carried upwards in the hot current of air, 
after having been detached from the crucible. The author found, by ex- 
periment, that, when a good platinum crucible was heated for twelve hours 
continually, it lost 0 016 grm. in weight, and its surface appeared as if 
etched, or as the well-known moire metallique. This loss and alteration are 
not due to the presence and subsequent elimination of osmium, because the 
loss is greater of the crucible than the quantity nf osmium contained in 
crude platinum. The brighter and more polished the surface of platinum 
crucibles and other platinum vessels exposed to ignition is kept, the better 
they will resist the deleterious action of the flame. 
What is Ccollpa f — By this name Herr Schickendantz understands (says 
the “ Chemical News”) a saline efflorescence, not unfrequently met with in 
certain parts of the slopes and along the rivers originating in the Cordilleras 
de los Andes. The author gives (“ Annalen der Chemie,” Sept.) at great 
length, details of the analysis of several samples of this substance, which, 
setting aside impurities present only in small quantity, consists, in 100 parts, 
of — soda, 45-21; carbonic acid, 28-99; water, 25-70; agreeing nearly with 
the formula Na 2 C 2 0 3 + 2H a O. Another sample consisted mainly of — water, 
35-28; soda, 38*28; carbonic acid, 26-44; nearly agreeing with the formula 
Na 2 C 2 0 3 + 3H 2 0. The author resides at Pilciao, province of Catamarca, 
Argentine Republic. 
Influence of Light on Petroleum . — According to the researches of M. Gro- 
towski (published in a recent number of the journal which the siege of Paris 
has cut off from us, “ Cosmos ”), when the petroleum oils are exposed to the 
solar light under certain conditions, they absorb a certain quantity of 
oxygen, and convert it into ozone in a similar manner to what has been 
observed in connection with other hydro-carbons. The oxygen does not 
seem to combine with the oil, but reacts energetically as an oxidizer upon 
substances with which it is brought in contact, thus the cork of the vessels 
in which it is contained is generally acted upon to some considerable extent. 
After the action of the ozone, the oil boils with difficulty. The colour of 
the vessels in which the oil is placed has a great deal to do with the absorp- 
tion of the oxygen. 
What is the Active Principle of Picinus Seeds ?■ — Herr E. Werner has taken 
up this subject since Dr. Tuson’s papers have been published, and after referring 
