November 10, 1922] 



SCIENCE 



537 



tight cover. This is made possible by tacking 

 a tongue of half-inch stripping around the edge 

 of the cover to fit into a trough at the top of 

 the walls. The tongue and trough are painted 

 matt black, a little lampblack in weak alco- 

 holic shellac answering for this purpose. The 

 interior of the bos need , not be painted, 

 although a white coat affords a better view of 

 manipulations in the interior. 



To view what is going on inside the box two 

 small windows are provided at the level of the 

 eye when the box is set on a table. The window 

 in front is of clear ru'by photo-safe glass, the 

 one opposite is either of ruby glass or trans- 

 lucent ruhy fabric. Behind the rear window 

 is placed an electric bulb operated by a switch 

 inside. Another inside switch controls a socket 

 on one wall which may interchangeably have a 

 low candle-power light for lantern slide making 

 or a high power light for exposing develop- 

 ment papers. A shelf located midway across 

 the end is an added convenience. The entire 

 cost for materials is five dollars; a few hours 

 of labor can construct the box. 



A secret of continued success in using this 

 small darkroom ds to keep hypo away and thus 

 avoid contamination. This is possible lay hav- 

 ing a tray containing weak acetie acid, about 

 2 per cent., into which is to be immersed 

 plates, slides, films or prints as fast as they 

 are developed. The acid checks the action of 

 the developer and permits the quick removal 

 of the light-sensitive materials from the de- 

 veloping ibox to the hypo bath outside without 

 danger of fogging. Developed material can be 

 left in the acid hath until it is convenient to 

 open the box. 



The idea of a developing box is not new. 

 There are small developing tanks and boxes on 

 the market for daylight use hy the time method 

 of development. Convenient changing bags of 

 cloth have long been employed 'by the traveler. 

 Developing boxes equipped with sleeves and 

 ruby glass are available with X-ray outfits. 

 Undoubtedly the urgency of the war period for 

 rapid photographic production led to the con- 

 sti-uetion of portaible darkrooms. But the sim- 

 plicity, adaptability and convenience of the 

 aibove-described miniature darkroom are so 

 great that the writer will be pardoned, even 



though his discovery is not new, if this an- 

 nouncement will acquaint others with a worth- 

 while piece of equipment. 



A. L. Melandbr 

 State College op Washington 



THE VALUE OF COST ACCOUNTING IN 



ANALYTICAL AND CONSULTING 



LABORATORIES 



This subject has had very little, if any, con- 

 sideration in the past. The probable reason 

 for this neglect appears to be the comparative- 

 ly small field for analytical and consulting 

 laboratories. 



Through the long association with this field 

 the writer has worked out an elaborate system 

 of cost records which have proved most valu- 

 able in the determination of a fair price to 

 clients as well as a fair return to the owners. 

 This system produces such information as will 

 show what work is profitable and what kinds 

 of analytical tests are unprofitable; the reasons 

 for the profits or losses are readily revealed 

 after a persistent tabulation of the records. 



The latter information serves to permit the 

 preparation of sliding scale prices, i. e., for 

 one test, for two tests, for three tests, etc. It 

 also reveals the comparative fluctuations in the 

 costs on a given test. This variation in costs 

 should always be treated with the utmost care, 

 as when a worker becomes so proficient that he 

 does not require the assistance of any of the 

 usual factors in a laboratory, and finishes the 

 job in record time, the owner as well as the 

 client is entitled to a little of this efiiciency in 

 dollars and cents. The owner should weigh 

 the costs in these cases against the reasons why 

 that worker is proficient in making these cer- 

 tain tests and allow himself leeway for either 

 the replacing of that man or the increasing of 

 his salary. An efficient and speedy worker 

 generally secures his knowledge by repetition 

 principally, by use of the owners' books and the 

 supervision and advice of his chiefs. In other 

 words, the speed and efficiency of one worker 

 is not the only 'basis for costs. 



The costs when compiled in a comparative 

 form will readily show the variations, the 

 causes being numerous. Some of them are 

 represented in the unfamiliarity with the 



