1893.] NEW YORK ACADEMY OF SCIENCES. 133 



1624. This pharmaceutical work contain nineteen full-page 

 plates engraved with delicate skill. 



InKircher's Miindus Subterraneus (1665) are engraved numer- 

 ous forms of furnaces and stillatories, lai'gely copied from 

 Donato d' Eremita's work. 



J. J. Beclier, in his account of a "Portable laboratory" 

 (1719), exhibits on a single plate sixty-four different articles, 

 including the following : Crucibles, muffles, cupels or tests, 

 moulds for making cupels and for casting metals, mortars, 

 mills for grinding, bellows, tongs, forceps, a tripod for support- 

 ing dishes, a rabbits-foot for brushing powders, a hand screen 

 to protect the face from heat, various vessels of wood, copper, 

 and iron, scales for Aveighing (three styles), retorts, phials, 

 funnels, bladders, besides an apron, a towel, a linen jacket, an 

 hour-glass, candles and tobacco-pipes ! 



Straw-rings for supporting round-bottomed vessels are 

 pictured in Lefevre's Traite (1669). 



The interior of the University laboratory at Utrecht, under 

 the direction of Johann Conrad Barchusen, Professor of 

 Medicine and Chemistry, is neatly figured in his Pyrosophia, 

 published 1698. In this, as in others of the period, the promi- 

 nence given to furnaces reflects the importance attributed 

 to operations by fire. 



Physical instruments of chemical application were slower in 

 developing ; thermoscopes appeared early in the seventeenth 

 century and thermometers somewhat later.* Torricelli dis- 

 covered the barometer in 1643, and Pascal tested its utility on 

 the Puy-de-Dome five years later. 



Otto de Guericke's air-pump and frictional electric machine, 

 together with the interesting experiments conducted with the 

 Magdeburg hemispheres are handsomely depicted in his 

 celebrated treatise De vacuo spalio, published in 1672. This air- 

 pump and the hemispheres are preserved in the Royal Library, 

 Berlin. The Hon. Robert Boyle improved Guericke's air-pump 

 in 1659, and used it in laying the foundations of pneumatic 

 chemistry, a field that from this time occupies our attention 

 almost exclusively. Boyle's air-jDump and accessory apparatus 

 are figured in plates accompanying the several editions of his 

 works. 



As is well known the earlier chemists paid little or no atten- 

 tion to gases though they were familiar with processes which 



*Geber remarks that " Fire is not a thing which can be measured, therefore 

 it happens that error is often committed in it." He evidently felt the need of 

 thermometers- 



