3/0 Optical Improvement. — Galvan'?fm. 



conclufions upon the phaenomena prefented by its faline 

 compounds. 



In faturating the refiduum of ether, mixed with water, 

 with carbonate of lime, he obtained a foUuion which gave 

 by evaporation a fait that cryftallized in parallelopipeds, 

 having but little tafte, and being foluble in ico parts of cold 

 water. This fait was decompofed by fulphuric acid. By the 

 aftion of oxygen gas, or of nitrous acid, it was converted 

 into fulphatc of lime; and, by being healed with charcoal, 

 it gave a fulphuret of lime. 



When it was mixed with a folution of carbonate of pot- 

 afli, foda, or ammoniac, a double decompofilion took place, 

 and the fironger acid combined with the alkalies. 



Mr. Dabit has noticed fome of the properties of its alka- 

 line combinations, which are extremely analogous to thofe 

 of the fulpbifes, He propofes to call the acid the oxygenated 

 fulphureous acid. But the application of the name will moft 

 probably be generally conficiered as premature; and new 

 rharafters will be required to diftinguifh it from the ful- 

 phureous acid, before its exiftence as a peculiar body can be 

 implicitly admitted. 



6. Dr. Benzenberor, in an eflay on the improvement of 

 pbjecl glaffes for telefcopes*, warmly recommends that the 

 glafs be fuSered to cool in the pots without ftirring, an4 

 that the mafs be then divided in a horizontal direftion, fo 

 that the variation of denfity may be regular, and then, by a 

 proper form of the glaffes, the errors of refraftion may be 

 porreded. The idea is not new, but it does not appear to 

 have been carried into practice. Dr. Benzenberg confiders 

 achromatic telefcoces as promifing much more than reflec- 

 tors, and thinks that they intercept much lefs light. 



7. Mr. Sprcnger of Jever gives an accountf of his method 

 of adniinificring Galvanic elertricity in cafes of deafnefs. A 

 fm<all ball is aii])lied to the external orifice of the ear, and a 

 much larger one is held in the patient's hand ; the conmiu- 

 nication is then formed and interrupted alternately by means 

 of machinery, once in every fecond, for about four minutes 

 daily, for a fortnight or more. He aflerts that he has thus 

 reflored the ienfe of hearing to forty-five perfons, and to four 

 of them that of fmell alfo. All who were completely deaf 

 experienced relief, almoft without exception; but a partial 

 deafnefs did not appear to receive the fame benefit. The ear 

 was filled with wool, to avoid takinc cold. The decree of 

 advantage obtained was eftimated by an inftrument invented 



* Gilbert's Aniials. f Ibid. 



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