Page:Scientific Memoirs, Vol. 1 (1837).djvu/77

Names of the substances interposed. (Those plates whose thickness is not specially indicated have the common thickness of 2mm·6.)	Transmissions out of 100 rays.
	Rays immediately from the lamp.	Rays emerging from the alum, (thickness 2mm·6.)	Rays emerging from the sulphate of lime, (thickness 2mm·6.)	Rays emerging from the chromate of potash, (thickness 2mm·6.)	Rays emerging from the green glass, (thickness 1mm·85.)	Rays emerging from the black glass (thickness 1mm·85.)
Rock salt	92	92	92	92	92	92
Fluate of lime	78	90	91	88	90	91
Beryl	54	80	91	66	70	57
Iceland spar	39	91	89	56	59	55
Glass (thick. 0mm.5)	54	90	85	68	87	80
Glass (thick. 8mm)	34	90	82	47	56	45
Rock crystal	38	91	85	52	78	54
Chromate of potash	34	57	53	71	28	24
Sulphate of barytes	24	36	47	25	60	57
White agate	23	70	78	30	43	17
Adularia felspar	23	23	58	43	50	23
Yellow amber	21	65	61	20	13	8
Black opake mica (thick. 0mm9)	20	0·4	12	16	38	43
Yellow agate	19	57	64	24	35	14
Emerald	19	60	57	26	20	21
Borate of soda	18	23	33	23	30	24
Green tourmaline	18	1	10	14	24	30
Common gum	18	61	52	12	6	4
Sulphate of lime	14	59	54	22	9	15
Sulphate of lime (thick. 12mm)	10	56	45	17	5	0·4
Carbonate of ammonia	12	44	34	11	6	5
Citric acid	11	88	52	16	3	2
Tartrate of potash and soda	11	85	60	15	2	1
Alum	9	90	47	15	0·5	0·3
Coloured glasses, (common thickness 1mm.85.)
Glass, white	40	90	83	50	67	55
— violet	34	76	72	42	56	47
— red	33	74	69	41	54	45
— orange	29	65	58	36	48	39
— green (apple)	25	3	20	22	55	50
— green (mineral)	23	1	15	19	52	58
— yellow	22	49	46	27	35	30
— blue	21	47	42	26	34	29
— black (opake)	16	0·5	18	11	42	52
— indigo	12	27	26	14	20	17

Vol.. I. — Part I.