SCIENTIFIC SEMMAET. 
93 
witli strong- solution the colour is so intense as to be almost black. When 
diluted the shade is magnificent, rivalling tlie aniline red in richness. I 
have already stated within what limits ruthenium can be detected by hypo- 
sidphite of soda. I now subjoin the limits observed with respect to hypo- 
sulphite of soda. A solution containing one four-thousandth of hyposulphite, 
gave a clear rose red. One containing one twelve-thousandth gave a well 
marked pink liquid. One containing one twenty-five-thousandth gave a 
salmon colour. The experiment was not carried further because the salmon 
colour in the last-mentioned trial showed that the test had then reached its 
practical limit. I do not doubt that with even one hundred-thousandth a 
colouration could be obtained, but it would not have the specific distinctness 
given by the carmine and rose shade previously described.” — Vide American 
Journ. of Science, September. 
Conversion of Wood-Spirit into Aklehyd. — At the meeting of the French 
Academy on September 30, M. Dumas presented a memoir of Dr. Hofmann’s, 
in which the author described how he obtained the transformation of wood- 
spirit into aldehyd — a problem which had failed in the hands of MM. Peligot 
and Dumas : — Dr. Hofmann placed in a sufficiently long tube a spiral of 
platinum, which he raised to the temperature of incandescence by means of 
a voltaic current; then he traversed the tube by a continuous jet of the 
vapour of wood-spirit ; this vapour is sufficiently heated to be decomposed, 
and transformed into aldehyd, which can be collected in the form of a con- 
tinued stream. The operation can be continued for several days, and it has 
been proved that more than two-thirds of the wood-spirit is converted into 
aldehyd. — Vide Comptes Hendus, Sept. 30. 
CliemicalUxamination of Siliceous Minerals . — In a recently-published paper 
on the investigation of certain New Zealand minerals, Mr. W. Skey pointed 
out that the methods now in vogue among chemists are liable to numerous 
errors. After giving numerous details which we have not space to repro- 
duce, he draws these conclusions : — First, that the present mode of ex- 
tracting phosphoric acid from siliceous minerals for estimation is radically 
wrong, or at least very imperfect, much of the phosphoric acid these minerals 
may contain being determined to their silica when recently precipitated, if 
not already in combination therewith. Secondly, that in the great majority 
of the analyses of silicates, &c., the silica therein is given a trifle too high ; 
and, lastly, that phosphoric acid exists in larger quantity and is even, more 
widely distributed through the mineral kingdom than has hitherto been 
suspected — circumstances possessing some degree of interest in connection 
with both mineralogy and agriculture. — Vide Chemical News, Oct. 11. 
Jdhosphoric Acid and Nascent Hydrogen . — In the Zeitschrift Analyt. Chemie 
[vi. 203] Herr Fresenius takes Mr. Herepath to task for his assertion that 
‘^phosphoric acid is reduced by zinc and sulphuric acid, so that hydric phos- 
phide is mixed with the hydrogen evolved.” Herr Fresenius has tried the 
experiment very carefully, but he has failed to And the result alleged by 
Herepath. 100 grammes of zinc were slowly dissolved in diluted sulphuric 
acid in presence of 10 grammes of sodic phosphate. The gases, after passing 
a small wash-bottle containing water, were conducted through two U tubes 
fllled with a neutral solution of argentic nitrate. A small quantity of black 
precipitate was formed, which, on examination, was found to contain arsenic 
