‘ 
On setting Cutting Instruments. 119 
a phenomenon which is fatal to the inference he had just before 
deduced, and conclusive with respect to the opinion’ I have pre- 
sumed to maintain. 
** Saggittam flamme impositam tene durante spatio decem 
pulsuum, ea deinde exempta comperies partes saggitt@ exte- 
viores versus flammum magis ustulatas et nigricantes maxi- 
maque ex parte in carbonem versas; cum in medio quod fuit, 
videatur duntaxat libatum igne,” &c. 
This last is a fine experiment; and if properly managed, the 
splinter of wood or other material may be withdrawn from the 
flame, the central part untouched. 
In reference to aphlogistic phenomena in the article “ Com- 
BusTION,” in Dr. Ure’s Nicholson’s Dictionary of Chemistry, the 
following occurs: ‘‘ Platinum and palladium, metals of low con- 
ducting powers and small capacities for heat, alone succeed in 
producing these phenomena.” Now I am confident Sir H. Davy 
would not wish a compliment paid to him at the expense of éruth, 
and on these terms I am also certain Dr. Ure would not deire to 
bestow it. Sir H. Davy not finding other metals ‘ succeed in 
producing these phenomena,” was perfectly justified in maintain- 
ing this opinion in his beautiful Researches on Flame. But in 
1819, I mentioned (see Annals of Philosophy) that Sig. Semen- 
tini at Naples had found that silver and copper (metals of high 
conducting powers in relation to heat) exhibited aphliogistic phe- 
nomena as well as platinum, &c. I would therefore simply put 
the question, ‘* Did not Professor Sementini show Sir H. Davy 
these experiments during his sojourn at Naples, as well as to my- 
self ?”’—I presume this to satisfy Dr. Ure. 
Sig. Sementini was so good as to favour me with a portion of 
silver wire the size he had found successful; and on my return 
to Paris, I showed the experiments with the si/ver rings reposing 
on camphor to Mons. Robiguet and other Scavans, and in this 
country also to several of the Professors of the University of 
Aberdeen. I have the honour to be, sir, 
Your most humble and obedient servant, 
J. Murray. 
XXX. On setting Cutting Instruments. 
Tur thanks of the Society for the Encouragement of Arts, Ma- 
nufactures, and Commerce, were last Session voted to George 
Reveley, Esq. of Queen-square, for a communication on the use 
of soap instead of oil in setting cutting instruments on a hone. 
It sets quicker, gives a good edge, removes notches with great 
facility, and is a much more cleanly material than oil. The 
operation is performed as follows ; 
Having 
