18 "
18.--Citric acid. 60 grains.
Carbonate of magnesia. 38 "
Citrate of potash. 68 "
Oxalate of potash. 22 "
_A more Intense Blue Black._
19.--Citric acid. 30 grains.
Carbonate of magnesia. 18 "
Citrate of potash. 100 "
Oxalate of potash. 33 "
_A Clearer Blue._
20.--Citrate of potash. 136 grains.
Oxalate of potash. 44 "
In the photographic exhibition at Florence, the firm of Corvan[1]
places on view a frame containing twenty proofs produced by the
foregoing twenty formulae, in such a way that the observer can compare
the value of each tone and select that which pleases him best.--_Le
Moniteur de la Photographie, translated by British Jour. of Photo._
[Footnote 1: Does this mean Mr. A. Cowan?--_Translator._]
* * * * *
NOTE ON THE CONSTRUCTION OF A DISTILLERY CHIMNEY.
At a recent meeting of the Industrial Society of Amiens, Mr. Schmidt,
engineer of the Steam Users' Association, read a paper in which he
described the process employed in the construction of a large chimney
of peculiar character for the Rocourt distillery, at St.
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