HOW TO MAKE BLUE-PRINT PAPER 183 



arranging your records in orderly columns. As time 

 goes on, the arrangement in columns permits an easy 

 reference to past observations, and all the records of the 

 same kind are together. The government of the United 

 States is continually making records of the weather and 

 these observations save millions of dollars every year to 

 farmers and ship owners. 



70. How to Make Blue-Print Paper. 



While blue-print paper may be purchased at a small 

 price, it is often desirable to prepare certain kinds of 

 psper so that prints may be made on them. Another 

 use of the mixture is to apply it to cloth. Simple cotton 

 cloth soaked in it may be printed upon in the same man- 

 ner as upon paper. A collection of prints of leaves may 

 be made and the different pieces may then be sewed 

 together to form a pillow cover. The solutions should be 

 made as follows: 



Solution A. Distilled water 125 cubic centimeters.* 

 Potassium Ferricyanide 25 grams. 

 Gum Arabic 2 grams. 



Solution B. Distilled water 125 cubic centimeters. 

 Iron ammonia citrate 37 grams. 

 Gum Arabic 2 grams. 



Use equal parts of A and B, mixing them only in the 

 dark. Candle light may be used. The two solutions are 

 not affected by light until they are mixed. Paper which 

 has no coating upon it should be used. The mixture may 

 be applied in two ways it may be poured upon the paper 

 * See Sections 58 and 59 for information in regard to 

 measuring and weighing. 



