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[ 2 ] the dexterous management of the blowing-pipe, requires a great deal of experience and (kill, and will certainly be prejudicial to the breads of fuch gentlemen as have any complaints relative to their lungs. Befide thefe obje&ions, the habit of pro perly managing this inftrument cannot be eafily ac quired in a certain age; and, if great precautions are not taken, an operator is apt to fwallow the fumes which arife from the operation, and which are often arfenical, or otherwife noxious. We have therefore taken all poffible care to avoid any fuch operations as would require a great deal of trouble, or a larger apparatus than may be taken on a journey or voyage without too much incumbrance. Upon the whole, it would not be amifs to take Mr. Engftroem’s apparatus, as it contains a great variety of inftruments we muft likewife recom mend ; viz. a hammer, a fteel to ftrike fire with, a loadftone, a file, a fteel plate to hammer and pound fubftances on, a magnifying-glafs, a finall mattrafs, a trough for wafhing the ores, &c. The only additions we fhould chufe to make, would be a fmall box containing fome phials with the following liquids •, viz. Three phials with the con centrated acids of vitriol, marine fait, and falt- petrc, together with one phial full of aqua regis, which is a compound of two-thirds of acid of nitre and one-third of muriatic acid, or in fome cafes of equal parts of each of the above acids ; 2. A folution of fait of tartar; 3. Spirit of hartf- horn, or a volatile alkali; 4. A phial with liquor vini probatorius*; 5- Some oil of olives, or lin- * Take one ounce of orpiment, two ounces quick lime, twelve ounces diftilled water, infufe the above fubftances with the water, digcft the infulion in a clofe glafs, in a moderately warm place, fhake it often during twenty-four hours, let it cool, decant it, keep it in a well Hopped glafs; this is liquor vini probatorius. feed,