THIS little Hand-book is intended to supply manufacturing chemists, dyers, drysalters, druggists, brokers, and all persons interested in the chemical arts, with directions for the assay and valuation of those articles of commerce which come into their hands. For this purpose the best and simplest methods have been selected, and stated, it is hoped, with the needful clearness.
The impurities-accidental or intentional-found in each substance are also noted. Articles of food are not included in the plan of the work. To this, the main portion of the manual, has been added a brief course of quantitative analysis, and an Appendix of Chemical Tables. The purpose of the work being merely technological and commercial, many of the niceties and precautions required in abstract research have been necessarily omitted.
POUNDING (pulverization, porphyrization).-The substance to be examined, if a solid, is reduced to fine powder in a mortar of Berlin ware, or, if very hard, in one of agate. Some minerals can be powdered only if first heated to redness and plunged suddenly into cold water. Tough substances are wrapped up in stout paper, and bruised with a hammer before being placed.
