506 PHILOSOPHICAL TRANSACTIONS. [anNO I76O. 



LXXX. .Abstract of a Letter to Mr. Benjamin TVilson^ F. R. S. concerning 

 Electricity \ from Mr. Torhern Bergman^* of Upsal. p. 907. From the 

 Latin. 



Dr. Franklin, in the 28th article of his 3d letter, wonders that a piece of 

 ice, or an icicle, does not transmit the electric virtue, since water does it so 

 well. But I, says Mr. B., have made some experiments, which show that a 

 small quantity of water is not sufficient for this purpose. Thus, take a glass 

 tube of 3 or 4 feet long, such as a barometer tube ; fill it with water, and 

 stop both ends by a perforated metal thread entering a little way into the 

 water, as appears in the _ 



annexed figure. If now ^^"^ 



two persons, disposed as in a circle for making an explosion, hold the ends of 

 the metal threads a, a, and try to make the evacuation, yet this will not per- 

 fectly take place, for hardly the wrist, and very seldom the elbow will be shocked 

 by this method. But augmenting the capacity of the tube, it transmits more, 

 until it thus increases, so as to permit a full and free passage. It follows, 



• This distinguished philosopher, who so greatly enlarged the bounds of chemical knowledge, and 

 introduced into chemical analysis a degree of exactness unknown before, was a native of Sweden, 

 and was born in 1735. He studied at Upsal, where he qualified himself for the medical profession, 

 and took the degree of m. d. It does not appear however that he ever engaged in the exercise 

 of the medical profession; but devoted himself to the pursuit of general science, and, after some 

 years, to the study of chemistry. In I76rhe was appointed professor of mathematics and natural 

 philosophy at Upsal j and about 6 years after, he succeeded Wallerius as professor of chemistry and 

 mineralogy in the same university. About this time (176?) he published in the Stockholm Trans- 

 actions his memoir on the crystallization of alum j and afterwards, for the space of 17 years, he 

 continued to publish from time to time (till within a year of his death, which happened in 1784) 

 various chemical dissertations, either separately, or in the Swedish Transactions before mentioned. 

 To the inexpressible regret of the philosophical world, his life, (like that of his contemporary 

 Scheele) was shortened by his unceasing application to chemical pursuits, he being only in his 49th 

 year, when he died. 



Among his principal works may be mentioned his Opuscula Physica et Chemica, 3 vols. 8vo j 

 his Sciagraphia Regni Mineralis ; his treatise De Attractionibus Electivis, (of all which there are 

 English translations) and his Physical Description of the Earth, 2 vols. 8vo. published in the 

 Swedish language. 



Ingenuity, accuracy, industry and method are conspicuous in all the writings of Bergman j his 

 labours were extended to a vast variety of subjects, in all of which he made large additions to the 

 stock of chemical knowledge. Had he done no more than publish his Treatises on Elective Attrac- 

 tion, on the Blowpipe, and on the Method of Assaying in the Humid Way, he would still have 

 ranked high among the chemists of the 18th century ; but when we call to mind his experiments on 

 earths, gems, and metals (including those on metallic precipitates), and his analyses of mineral waters, 

 and the methods of preparing them artificially, (not to mention his exjjeriments and observations on 

 the acid of sugar, the aerial acid, &c. and his improvements in nomenclature) we cannot but regard 

 him as one of the greatest^ chemists which any country or age has produced. 



