VOL. XC.] PHILOSOPHICAL TRANSACTIONS. 7§5 



appear, by looking through these glasses, that there is a difference in their disposition to transmit candle- 

 light or fire-light. 



Min. Fire. Orange glass. 



Exper. 125. 66" 66 



5 80 71 ... 14 : 5 = .357. It stops 643 rays of fire-heat. 



Min. Fire. Yellow glass. This experiment be- 



Exper. 126. 6l£ 6lJ ing made early in the 



5 83 68 1 ... 21 : 7f • cor. - 1£° . 20| : 6£ — .315 morning, before the 

 temperature of the room was come to its usual height, the assistant thermometers showed a gradual ris- 

 ing of 1^ degree in the 5 minutes : they are in general very steady. The glass stops 685 rays of fire-heat. 



Min. Fire. Pale green glass. 



Exper. 127. 65% 65| 



5 85 7 If . . . 19h ■■ 6 = .312 It stops 688 rays of fire-heat. 



Min. Fire. Dark green glass. 



Exper. 128. 68 68 



5 88f 73*- ...20 g : 5| cor. - 4°= 255. It stops 745 rays of fire-heat. 



Min. Fire. Bluish green glass. 



Exper. 129- 6'8£ 68£ 



5 87 74 1- . . . 18-J. : 5 J = .304. It stops 696 rays of fire-heat. 



Min. Fire. Pale blue glass. 



Exper. 130. 68£ 68 



5 S6£ 73| ... 17| : 5| = .324. It stops 676 rays of fire-heat. 



Min. Fire. Dark blue glass. 



Exper. 131. 67 67 



5 84-| 73 ... 17| : 6. cor. -1°= .296. It stops 704 rays of fire-heat. 



Min. Fire. Indigo glass. 



Exper. 132. 69% 69I 



5 85-a 73| .. . 16l : 4| = .279- It stops 721 rays of fire-heat. 



Min. Fire. Pale indigo glass. 



Exper. 133. 67^ 67k 



5 85-1 74 . . . 18| : 6^ . cor. - \° = .345. It stops 655 rays of fire-heat. 



Min. Fire. Purple glass. 



Exper. 134. 69 69 



5 83 73^... 14 : \\ = .321. It stops 679 rays of fire-heat. 



Min. Fire. Violet glass. 



Exper. 135. 66% 66'| 



5 86 j 74} . . . 20 : 7| = -385. It stops 615 rays of fire-heat. 



Min. Fire. Crown glass ; one side rubbed on emery. 



Exper. 136. 67i 67% This glass, so prepared, stops 723 scat- 



5 89| 73| . . . 22i : 6\ = .277. tered rays of fire-heat. 



Min. Fire. Coach glass ; one side rubbed on emery. 



Exper. 137. 68 67 1 



5 87^ 72\ . . . 19^ : 4-| = .242. It stops 758 scattered rays of fire-heat. 



-— ' Min. Fire. Crown glass ; both sides rubbed on emery. 



Exper. 138. 68| 68 



5 92f 73 . . . 23! : 5 = - 2 °9. It stops 791 scattered rays of fire-heat. 



Min. Fire. Coach glass ; both sides rubbed on emeiy. 



Exper. 139. 67 67 It stops 854 scattered rays of 



5 88 701 ...21 :3|. cor. - |° = .146. fire-heat. 



M'n Vrt* $ Crown glass. \ One side of each rubbed 



lVIin. fire. \ Coach glass./ on emery. 



Exper. 140. 66 66 These glasses stop 849 scat- 



5 86 69i ... 20 : 31 . cor . - 1 ° = . 1 5 1 . tered rays of fire-heat. 



Min PW / Crown glass. \ Both sides of each rubbed 



iviin. rire. \ Coach glass./ on emery. 



Exper. 141. 66| 66| These glasses stop 897 scat- 



5 83| 68| . . . 17 : If = .103. tered rays of fire-heat. 



M . The 4 glasses of the 2 preceding expe- 



lYLin. pure. riments put together. 



Exper. 142. 66 66 , These 4 glasses stop 902 scat- 



5 80 67-f ... 14 : 1-f = .098. tered rays of fire- heat. 



