130 



PHOTOGRAPHY 



the trousers the silver chloride would not be changed so much 

 as where the collar image is. The light from the face would 

 produce a still different effect, since the light from the face is 

 stronger than the light from the gray trousers, but less than 

 that from a white collar. The face in the image would show 

 less changed silver chloride than the collar, but more than the 

 trousers, because the face is lighter than the trousers, but not 

 so light as the collar. Finally, the silver chloride would be least 

 affected by the dark coat. The trees in the background would 

 affect the plate according to the brightness of the light which 

 fell directly upon them and which they reflected to the camera. 

 When such a plate has been developed and fixed, as described 

 in Section 12-1, we have the so-called negative (Fig. 83). The 



collar is very dark, the black 

 coat white, the clear blue sky 

 very dark. 



.The lighter the object, such 

 as sky or collar, the more salt 

 is changed, or, in other words, 

 the greater the portion of the 

 silver salt that is affected, and 

 hence the darker the stain on 

 the plate at that particular 

 spot. The plate shows all gra- 

 dations of intensity the sky is 

 dark, the black coat is light. 

 The photograph is true as far 

 as position, form, and expression are concerned, but the actual 

 intensities are just reversed. How this plate can be trans- 

 formed into a photograph true in every detail will be seen in 

 the following Section. 



124. The Perfect Photograph. Bright objects, such as 

 the sky or a white waist, change much of the silver chlo- 



FlG. 83. A negative. 



