GENERAL NOTES I 35 



wish perfection and permanency in their neg- 

 atives. A formaldehyde bath, in the propor- 

 tions of one drachm to eight ounces of water, 

 answers the same purpose as alum and in a 

 better manner. It is my own favorite means 

 of hardening a film. An excellent method of 

 preventing the film from breaking off around 

 the edges is to rub it to the depth of about 

 one-eighth inch with a piece of soft paraffine 

 wax before development. 



Box for Fixing Bath. If but a few nega- 

 tives are made at one time, a hard-rubber or 

 agate-ware tray will answer quite well for 

 holding the hypo bath, as was pointed out 

 in the chapter on negative making. The 

 principal objections to such a receptacle are 

 slower and less even fixation, and the in- 

 creased danger of scratching or otherwise 

 defacing the moist and tender films. A 

 grooved box, in which the plates stand on 

 edge, is far better in every way. But you 

 are warned to be very careful in selecting 

 such a box, to see that it is made of hard 

 rubber, which will be found practically inde- 

 structible. On no account take one of papier 

 mache. It may look better and cost less 

 than the rubber one, but is a delusion and a 

 snare. The sharp edges of plates when low- 



