REFRACT>ON. 



The refraftivc power of fome other fl 

 fecond pair of Menifcufes, i8tli AugiiR, 

 tlierniometer being 31 degrees above the fn 



uitls found by the 

 1761, Reaumur's 



ez'ing point. 



The fine of tlie an- 

 ple uf incidence 

 - of 



A ray of light paffing from air into 



Well-water 



Four different folutions of nitre, viz.. 



Twelve grains of depurated nitre to an 



ounce of water 

 Twenty-four grains of di-purated nitre to 



an ounce of water 

 Thirty-eight grains of depurated nitre to 



an ounce of water 

 Thirty-eight grains of depurated nitre to 



two ounces of water 

 Four different infufions 



of parfley 



of nutfhclls 



of faffron 



of fifh-fcales 



of Zeltzer water 



of Eger water 



will be to t)ii 

 rcTrai^ioii as 



'•335O 



'•33'^o 

 '•3398 

 '•3450 



1.3540 .v. 



'•3355 

 '•3359 

 1-3363 

 '•3353 

 '•3353 

 '•3358 

 1.3650 



1-3757 

 1.4088 



o 



A ray of light palling from air into 



"Water - - 



Spirit of honey 



Spirit of fal ammoniac 



Oil of amber - - 



Spirit of liartlhorn 



Human urine 



'White of an egg 



Jelly of hartftiorn 



French brandy 



Spirit of wine 



Diftilled vinegar 



Gum ammoniac 



Aqua regla 



Ditto from aqua fortis and fal ammoniac 



Aqua fortis - - 



Spirit of nitre 



The cryftalline humour of an ox's eye 



Butter of antimony 



Oil of vitriol 



Oil of wax 



Oil of lavender 



Oil of rofemary 



Oil of origanum 



Oil of ginger 



Oil of oranges 



Oil of turpentine . 



Oil of favine 



1-3359 

 1-3359 



1-3377 

 1-3377 

 1.3390 



1-3419 

 1-35" 

 1-3541 

 1.3626 



1.3721 

 1.3721 



1.3898 

 1.3964 i> 

 1.4044 

 1.4076 



1-4635 

 3.6831 

 1.4262 

 1.4524 

 1.4960 

 1.4.719 

 J.4770 

 1.4799 



'-4833 



S-4S33 

 '•4857 J 



The fincof ilie an- 

 gle of incidence 

 will be 10 iliat o( 

 riffra^ion as 



1.4878" 

 I.491I 

 1. 5010 

 1.5088 

 I.5114 

 1. 5136 



1.5340 



'•5443 J 



Tiic refraftivc powers of fome Iranfpareiit liquors accord- 

 ing to the obfcrvalions of fir Ifaac Newton. .See Optics, 

 1'- 247- 



Oil of flowers ot miiil< 



Oil of mint 



Oil of amber 



Oil of cummin 



Oil of fennel 



Oil of cloves 



Oil of anife 



Oil of cinnamon 



Oil of faffafra-J 



s 

 o 



Anodyne liquor 

 Spirit of camphor 

 Spirit of Saxon fope 



That the refraftive power of thefe fluids, thus determined 

 by M. Euler, may be more eafily compared with Mr. 

 Haufltbee's and fir Ifaac Newton's experiments, he reduced 

 the refult of their obfervations into the following tables, 

 exadlly fimilar to his own. 



The refradlive .power of certain fluids found by Mr. 

 Haukfbee, fee his Experiments, p. 292. 



The fine of the an- 

 gle of InciHcnc- 

 will be to that of 

 refra{5^ion as 



See Prieftley's Hift. of Light, &c. p. 479, &c. 



V/hence the different refractive power in different fluids 

 arifes, is not- determined. Sir Ifaac Newton fliews, that in 

 many bodies, e. gr. glafs cryftal, a felenites, pfeudo-topaz, 

 &c. the refractive power is proportionable to their denfities ; 

 only in fulphureous bodies, as camphor, linfeed oil, olive, 

 amber, fpirit of turpentine &c. the power is two or three 

 times greater than in other bodies of equal denfity ; yet 

 even thefe have the refraiftive power with refpect to each 

 other nearly as their denfities. 



Water ha; a refradti\e power in a middle degree be- 

 tween thofe t-A-'O kinds of fubftances, and is, probably, of • 

 a middle nature. Salts and vitriols have refractive powers 

 in a middle degree between thofe of earthy fubftances and 

 water, and accordingly are compofed of thofe two forts of, 

 fubftances. Spirit of wine has a refraftive power in a 

 middle degree between thofe of water and oily fubftances ; 

 and accordingly feems to be compofed of both, united by 

 fermentation. It appears, therefore, that all bodies feem. 

 to have their refractive powers proportional to their den- 

 fities, or very nearly, excepting fo far as they partake of 

 more or lefs fulphureous oily particles, and there'by have 

 their refraftive powers made greater or lefs. Whence it 

 feenis reafonable to attribute the refraftive power of all 



bodies 



