4<*' Ca!vamfm.-~Pnme Numbers. 



very Utile leflened by momentary immerfion in water. Hence the increafe of cffeft 

 cannot much depend on the increafed temperature of the plates. 



3. Copper and zinc aft very powerfully with nitric acid. Iron and zinc feera to a£k 

 nearly as intenfcly with muriatic acid as with nitric acid. 



The galvanic combinations that I have been lately moft in the habits of ufing, are leries 

 of glafles conftrufted with zinc plates, filver or iron wire, and folutions of red fulphate or 

 riniriatc of iron. Thefe combinations a£l for a long time intenfcly ; fix or eight glaflei 

 being capable of flowly decompofing water ; and if their a£lion is at any time dlminiftied 

 from the depofition of oxyde of iron on the zinc plates, it may be eafily reftored by the ad- 

 dition of a little acid to the folution. 



4. I noticed in a former paper the conducing powers of charcoal, when made part 

 of the galvanic circuit *, I lately fet up a feries of eight glafles, with fmall pieces of well 

 burnt charcoal, zinc, and folution of red fulphate of iron ; the charcoal and zinc being 

 conne£ted by filver wire. This feries gave fenfible (hocks, and rapidly evolved gafes from 

 water; whilfl: an equal feries with filver and zinc produced much weaker effcfts. Hence 

 it would appear that charcoal and zinc are equal, if not fuperior, to any metallic com- 

 binations. 



•#* In my laft paper two errors occur, which require to be correfted. Page 340, line i9, 

 for -5% read -^%; and page 341, line 11, for proportional read in great meafure prtf 

 portional. 



III. 



On the Quotients arifmg from the Divijion of an Unit by prime Numbers. ■ By, 



i7. GoobWYs, Efq. 



To Mr. NICHOLSON. 

 SIR, 



JL HE following account of the quotients arifing from the divifion of an unit, &c. by 

 prime numbers, being, I believe, perfe£l;ly new, and promifing to be very ufeful, is very 

 much at your fervice ; and if you think it worthy a place in your Journal, it may induc« 

 the publication of a fmall table prepared for a farther elucidation of the fubje£i. 



I am, SIR, 

 ■q • Refpeftfully your's, 

 Eqft Smlthfield, 0£f. 1800. H. GOODWYN. 



* Dr. Wells, in an excellent paper on galvanifin, in the Phil. Tranf. has mentioned the great powers of 

 an are conipofed of charcoal and zinc, in exciting the limbs of fro^. 



Th« 



