50 TESTING MISCELLANEOUS SUPPLIES. 



successively, performing the operation as quickly as possible in order that the 

 time of settling may be approximately the same in the case of each sample. 

 Allow the cylinders to stand at rest in a place free from jar, and record from 

 time to time the height of the sediment formed by the deposition of the blacks. 

 When submitted to this test, a black which is suitable for the manufacture of a 

 canceling or stamping ink should occupy a volume of not less than 25 cc when 

 the sediment has stopped settling. 



3. Ash, etc. 



Blacks, dyes, and other substances used for the manufacture of canceling and 

 other stamping inks should be carefully examined to insure the absence of con- 

 siderable percentages of substances which are not essential to the production of 

 :HI ink of good quality. It can generally be assumed that the presence of con- 

 siderable quantities of any substance which does not actually contribute to the 

 desirable qualities of the ink will detract therefrom. Black pigments rich in 

 carbon of high specific gravity due to the presence of a large percentage of ash 

 are highly unsuitable for the manufacture of stamping inks. Only the concen- 

 trated brands of coal-tar dyes should be used, unless the substances with which 

 the less concentrated are diluted have been found to actually contribute to the 

 working qualities of the ink to be produced. 



TYPEWRITER RIBBONS AND CARBON PAPERS. 

 TYPEWBITER RIBBONS. 



The important things to be determined in a typewriter ribbon are length, 

 width, typefilling, character of record (and copy, if it is a copy ribbon), life 

 of ribbon, and resistance of record and copy to reagents and sunlight. 



1. Length and Width. 



Length and width are generally specified and should be stated on the report, 

 but the rating should be based entirely on quality. 



2. Typefilling. 



Tako a sufficiently long section of the ribbon on a suitable typewriter (for 

 wide ribbons use a Remington No. r and for narrow ribbons use an Under- 

 wood No. 5). Carefully clean tin- small letter r, and, using the standard paper 

 employed for ink testing, make records of this letter, striking the key with 

 as uniform a stroke as possible. Continue writing the letter c until the loop 

 fills so as to necessitate cleaning the type, or until 8,000 impressions have 

 been made. Ribbons which give 8,000 clear impressions are given a maximum 

 ratinir on typefilling, though the test may be carried as much further as may 

 be desired. 



3. Character of the Becord. 



The general eha met eristics of the record may be determined by examining 

 the sheets from the tyi^fllling test. Note color, clearness, whether the ribbon 



These are the machines thai were used in the test, but any others may be 

 employed for the purpose equally well, providing that the same machines are 

 used throughout the tests, otherwise the results would have no comparative 

 value. 



