266 



PHOTOGRAPHY 



face is stronger than the light from the gray coat, but less 

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

 show less changed silver bromide than the collar, but more 

 than the coat, because the face is lighter than the coat, but 

 not so light as the collar. Finally, the silver bromide would 

 be least affected by the dark tie. The wall paper in the back- 

 ground would affect the plate according to the brightness of 



the light which fell directly 

 upon it and was reflected to 

 the camera. When such a 

 plate has been developed and 

 fixed, we have the so-called 

 negative (Fig. 135). The col- 

 lar is very dark, the black tie 

 and gray coat white, and the 

 white tidy very dark. 



The lighter the object, such 

 as tidy 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 silver deposit on the plate at that particu- 

 lar spot. The plate shows all gradations of intensity the tidy 

 is dark, the black tie is light. The photograph is true as far as 

 position, form, and expression are concerned, but the actual in- 

 tensities are just reversed. How can this plate be transformed 

 into a photograph true in every detail ? 



The perfect photograph. Bright objects, such as the sky 

 or a white waist, change much of the silver bromide, and hence 

 appear dark on the negative. Dark objects, such as furniture 

 or a black coat, change little of the bromide, and hence appear 

 light on the negative. To obtain a true photograph, the nega- 

 tive is placed on a piece of sensitive photographic paper, or 



