LIPPMANN HELIOCHROMES—CAJAL. 247 
Fig. 12. Section through overexposed blue. The paleness of the 
lamine e and the absence of the mirror zone will be 
noticed. 
Fig. 13. Section through overexposed orange. 
The first lamina 7 is wanting, and the second is 
also rather pale. 
Fig. 14. Section through bright blue mixed with 
white; @ mirror zone, / fine secondary lamine. 
Fig. 15. Section through bright lemon yellow. 
The first lamine represent the phase of conversion 
into the mirror zone. 
Fig. 16. Section through underexposed and over- 
developed green, which corresponds to the shadow 
side of an orange. The fineness and transparency 
of the lamine, which are somewhat too dark in 
the reproduction, will be noted. 
Fig. 17. Section through the blue in a plate 
exposed without a mercury 
mirror. | 
COLORS MIXED WITH WHITE. 
Compound tones, such as 
gray, pink, cream, light blue, 
etc., formed by admixture of a 
principal color with white, oc- 
cur very frequently, and the ar- 
tistic value of the reproduction 
depends to a great extent on the 
correctness of the tonality of the 
latter. One may assume @ priori that the com- 
pound colors possess a better mirror zone, which 
gives the white, and secondly laminz with inter- 
vals corresponding to the principal color. This 
actually is the case, and proof is afforded in the 
section of a yellowish white (fig. 6). The surface 
of the plate shows the thin transparent mirror 
zone. Close behind is a fine pale stripe (¢), which 
perhaps belongs to the violet or blue, and then two 
or three thick lines separated from one another 
by wide intervals which correspond to the lamine 
of the yellow. 
Irregularities in the intervals between the lami- 
ne are frequently observed with compound colors; 
sometimes they are due to illusion and to unequal 
absorption of water. In those cases in which the water has acted for 
41780—08——20 
Fig. 17. 
