the filter, is collected upon dark
satinized paper; the filter itself is burned and the ash added to the
oxalate of lime. This oxalate of lime is then heated to a dark red
heat in a platinum crucible with lid until the oxalate of lime is
converted into carbonate of lime. By the addition of a few drops of
carbonate of ammonia solution and another slight heating of the
crucible, also the caustic lime produced in the filter ash by heating,
is reconverted into carbonate of lime, and after cooling in the
exsiccator, the whole contents of the crucible is weighed as
carbonate of lime, after deducting the known quantity of filter ash.

Any magnesia present in the filtrate of the oxalate of lime is by the
addition of a solution of phosphate of soda separated as phosphate of
ammonia and magnesia, after having stood twenty-four hours. The
precipitate is filtered off, washed with water to which a little
chloride of ammonia is added, dried, and after calcining the fiber and
adding the filter ash, glow heated in the crucible. The glowed
substance is weighed after cooling, and is pyrophosphate of magnesia,
from which the magnesia or carbonate of magnesia is calculated
stoichiometrically. All the ascertained sums must be multiplied by 2,
if they are to correspond to the analyzed and weighed quantity of ash.

The second half of the filtrate is used for determining the small
quantity of sulphate of lime still contained in the hydrochlorate
solution. By adding chloride of barium solution the sulphuric acid is
bound to the barytes and sulphate of baryta separates as white
precipitate. This is separated by filtering, washed, dried and weighed
in the customary manner. From the weight of the sulphate of baryta is
then computed the weight of sulphate of lime, which has passed over
into solution. The ascertained sum is also to be multiplied with 2.

The manufacture of roll tar paper from the roll paper was at first
found to be difficult, as it was impossible to submerge a surface
larger than from ten to fifteen square yards, rolled up, in the tar,
because more would have required too large a pan. Besides this, the
paper tears easily, when it is in the hot tar. All kinds of
experiments were tried, in order to impregnate the surface of the
paper without employing too large a pan.

The following method was tried at first: The roll paper was cut into
lengths of ten yards, which were rolled up loosely, so that a certain
space was left between th