JUNE 7, 1901.] 
gaseous products and some carbon. From 
these observations the following reduction pro- 
cess was evolved: A large iron pot is heated 
from below, so that a piece of tin dropped at 
the bottom will melt. The pot is ‘then filled 
with refuse fatty acids and the heat increased 
until they commence to give off vapors. Stan- 
nic dross is then introduced with stirring. 
This may be continued at pleasure or until the 
fatty acid is almost used up. The reduced tin 
is removed at convenient intervals. 
‘On Dr. Theodore Meyer’s Tangent System 
of Sulphuric Acid Chambers,’ by Chas. Glaser. 
The author described a modification of the con- 
struction and working of lead chambers used 
in the manufacture of sulphuric acid. The 
modification relates to the shape of the cham- 
bers and the motion of the gases. Ordinarily 
the chambers are square and the gases intro- 
duced in such a way that they traverse the 
chambers but once, get only moderate mixing, 
except where they fall upon the chamber cur- 
tains and where they are forced through rela- 
tively narrow connecting pipes between cham- 
bers. Inthe modification described, the chambers 
are round or polygonal, the gases are introduced 
near the ceiling in the direction of a tangent, 
and are removed through the center of the 
bottom by suitably constructed pipes. Experi- 
ments show that the gases move first along the 
sides of the chamber, drifting towards the cen- 
ter in such a way that the whole content gets 
into rotation. Cooling and draught bring the 
whirlpool in the center to the exit pipe. When 
introduced into the second chamber, the gases 
retain the revolving motion derived from the 
first, to which is added the motion of the second, 
so that an epicycloid motion is produced. The 
gases traverse the chambers a good many times, 
increasing largely the amount of work' per- 
formed. It has been demonstrated that by 
this method the necessary chamber space for 
one pound of sulphur in twenty-four hours’ is 
reduced to below ten cubic feet as against 
twenty in the old system. The author stated 
that the cost of producing sulphuric acid, soffar 
as labor and lead chambers are concerned, is 
reduced to fifty per cent. of what it was by the 
old method. 
‘The Solubility of Gypsum in Aqueous Solu- 
SCIENCE. 
wall 
tion of certain Electrolytes,’ by Frank K. 
Cameron and Atherton Seidell. 
This paper gave a description of the com- 
plete solubility curves for gypsum in aqueous 
solutions of sodium chloride, magnesium chlo- 
ride, calcium chloride, sodium sulphate and a 
mixture of sodium chloride and calcium hydro- 
gen carbonate at 25° C. With sodium chloride 
and magnesium chloride the curves show maxi- 
mum points. The formation of complex ions 
the authors believe to be possible and probable, 
but the deviations from the mass law are more 
likely to be due to a condensation of the sol- 
vent itself. 
With sodium sulphate it was shown that the 
solubility of the gypsum first decreased and 
then increased, with increasing concentration 
of the more soluble salt, until it became greater 
than in pure water. It is believed that a double 
salt was formed in the solutions, possibly iden- 
tical with the mineral glauberite. It did not 
separate from the solutions on evaporation, 
however, at ordinary temperatures. Here 
again the authors think the condensation of the 
solvent probably plays an important role and, 
under such circumstances, it is probable that 
the sodium sulphate dissociates to a large ex- 
tent or completely as a di-ionic electrolyte. 
The composition of the solid phase, containing 
both calcium sulphate and sodium sulphate, did 
not apparently affect the composition of the so- 
lution in contact with it. This is regarded as 
of sufficient interest to merit further investiga- 
tion. In solutions of calcium chloride the 
solubility of the gypsum decreases quite rapidly 
at first, and then very slowly but steadily as the 
concentration of the more soluble salt increases. 
When calcium carbonate in the solid phase 
was also in contact with solutions of sodium 
chloride, and was brought to equilibrium with 
ordinary air, it was found that up to concen- 
trations of about 80 grams per liter of sodium 
chloride, the gypsum dissolved in very nearly 
the same quantities as though the calcium car- 
bonate were not present. From this point on, 
however, the curve makes a sudden drop and 
then the solubility of the gypsum slowly de- 
creases. ; 
Applications of the results to geological and 
technical studies were indicated, and a theoreti- 
