OBSERVATIONS ON SALT. ^39 



V. 



Obfer rations on the Caufes why a large Quantity of common Salt 

 prevents Putrefaclion, and a fmall Quantity hajlens it. By 

 D. H. 



To Mr. NICHOLSON. 



S I R, 



JL HERE are few phenomena of nature more interesting, and Remarkable op- 



at the fame time more involved in obfeurity, than the twooppo- P°!i tl0I l of ef " 

 fl «. P • . r r , i-i-i i fectsof common 



lite actions or muriate or ioda, which is known to have very con- f a i t j n prcvent- 



fiderable effect, both in accelerating and in retarding putrefac- j n S or accelerate 

 tion. The antifepiic property of this fait has been known from as j ts quantit* & 

 the earlieft ages. It was difcovered, however, by Pringte, more or lefs. 

 Macbride, and Gardane, (hat putrefaclion may be haftened by 

 fprinkling the animal fubflances with water holding a fmali 

 quantity of muriate of foda in folution. This difcovery excited 

 much furprife; and the celebrated chemifts who obferved it 

 feem to have been fully aware of the difficulties attending its 

 explanation, as they have offered no theory to account for it. 

 Jt would doubtlefs appear a prefumptuous undertaking, to 

 attempt the folution of a queftion which has baffled the inge- 

 nuity of to many philofophers, did not the fubfequent difco- 

 veries in chemiftry and phy liology enable us to fpeculate on the 

 fubjeci with fome degree of probability. 



It feems neceffary for the decomposition of an animal fub- Putrefaclion re- 

 ftance, \ft, that it be in contact with atmofpheric air ; 2dly, that J^l]^' j 

 it be expofed to a moderate degree of heat ; and, 3dly, that it moifturej 

 be impregnated with, humidity. It muft neceflarily follow, 

 that whatever removes thefe conditions will check the progrefs 

 of putrefaction. Of this we have many inftances, as in the an( j ; s checked 

 effects of cold ; in covering the fubftances with fugar, refins, by fold and co- 

 &c. and in preferving them in fpirit of wine. I conceive with a^?" 2 f ° m 

 Gren, that muriate of foda acls only in this way, by abftracling Crude common 

 the moifturc, and removing the fubftance from the contact of falt fappofed to 

 oxigen; and not by a peculiar innate, and as it were hidden ? n gYndcovcrPg 

 (vis occulta) antifeptic power *. the body it is 



applied to. 

 * Grtn's Cherniftry, Chap. VIII. 



With 



