ABSORPTION SPECTRA OF THE ALKALOIDS. 
475 
Lines of cadmium, tin, and lead used for the interpolation curve. 
Scale- 
numbers. 
X. 
l 
T 
Scale- 
numbers. 
X. 
J. 
x 
Hundredths of 
Hundredths of 
an inch. 
an inch. 
0 
. , 
190-0 
Sn 
2812 
3556 
4-5 
192-5 
Pb 
2801 
3571 
20-5 
Cd(7) 
4414 
2265 
197-0 
Sn 
2778 
3599 
22-5 
Pb 
4386 
2280 
203-5 
Cd (17) 
2747 
3640 
30-5 
Pb 
4245 
2355 
213-0 
Sn 
2705 
3696 
4275 
Pb 
4061 
2462 
223-0 
Pb 
2662 
3756 
Air 
3994 
235-0 
Pb 
2613 
3827 
62-0 
Sn 
3800 
2503 
240-0 
Sn 
2593 
3856 
67-3 
Pb 
3739 
2674 
244-0 
Pb 
2576 
3882 
72-0 
Pb 
3683 
2715 
245-0 
Cd (18) 
2572 
3888 
76-3 
Pb 
3639 
2748 
245-5 
Sn 
2570 
3891 
79-0 
Cd (9) 
3610 
2770 
247-0 
Pb 
2561 
3904 
82-7 
Pb 
3572 
2799 
252-5 
Sn 
2545 
3929 
93-7 
Cd (10) 
3465 
2886 
- 266-5 
Sn 
2495 
4008 
97-0 
Air 
3437 
2910 
270-0 
Sn 
2483 
4027 
101-0 
Cd (11) 
3403 
2938 
272-0 
Pb 
2475 
4040 
106-5 
Sn 
3352 
2983 
281-3 
Pb 
2445 
4090 
109-5 
Sn 
3330 
3003 
282-0 
Pb 
2442 
4095 
115-0 
Sn 
3283 
3045 
286-5 
Sn 
2429 
4116 
118-0 
Sn 
3262 
3065 
289-0 
Sn 
2422 
4128 
119-5 
Cd (12) 
3260 
3067 
295-0 
Pb 
2402 
4163 
129-5 
Sn 
3174 
3150 
298-0 
Pb 
2393 
4178 
135-0 
Pb 
3137 
3187 
306-0 
Sn 
2368 
4223 
151-0 
Sn 
3033 
3297 
311-0 
Sn 
2355 
4246 
155-0 
Sn 
3008 
3324 
318-0 
Sn 
2335 
4282 
159-5 
Cd 
2980 
3355 
320-0 
Cd 
2329 
4293 
165-0 
Pb 
2949 
3391 
322-7 
Cd 
2321 
4308 
171-0 
Sn 
2912 
3434 
325-7 
Cd (23) 
2313 
4323 
177-0 
Cd 
2880 
3472 
335-0 
Cd & Sn 
2288 
4370 
178-5 
Pb 
2872 
3481 
344-0 
Cd (24) 
2265 
4415 
180-0 
Sn 
2862 
3494 
351-0 
Sn 
2247 
4450 
182-5 
Sn 
2849 
3510 
353-5 
Cd 
2241 
4462 
185-0 
Sn 
2839 
3524 
368-5 
Pb 
2205 
4535 
186-0 
Pb 
2832 
3531 
372-5 
Cd 
2195 
4555 
188-0 
Pb 
2822 
3543 
395-0 
Cd 
2145 
4662 
In this research the wave-length numbers have alone been quoted. The mode of 
proceeding after a series of photographs had been taken was, after measuring, to 
record and reduce the measurements to wave-lengths. The numbers obtained were 
then laid down on suitably ruled paper for the absorption curve to be plotted. It 
was then generally found necessary to execute a further series of photographs, and 
sometimes two or three series of the absorptions caused by more dilute or stronger 
solutions, in order to obtain the maximum and minimum effect of the absorbent 
suostance as well as the coefficients of absorption for all intermediate wave-lengths. 
The curves drawn are continuous, so that the necessity for shading is obviated ; the 
Unshaded diagrams are not such true representations of the photographs, but these less 
exact diagrams are supplemented by very careful and accurate descriptions. Authentic 
