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 the different coils.  These loose rolls, of course, occupied much space and could be put into the tar only in a standing position, because in a horizontal one the several coils would have pressed together again.  The loose roll was therefore slipped over a vertical iron rod fastened into a circular perforated wooden foot.  The upper end of this iron rod ended in a ring, in which the hook of a chain or rope could be fastened.  With the aid of a windlass the roll was raised or lowered.  When placed in the pan with boiling tar, it was left there until thoroughly saturated.  It was then taken out, placed upon a table, and the excess of tar allowed to drip off into a vessel underneath.  After partially drying, the roll was spread out in open air, occasionally turned, until sufficiently dried, when it was rolled up again.