The Class-Book of Chemistry. 63 



ments Youmans had often written for a liberal hon- 

 orarium. When the diagrams had been united in a 

 chart Mr. Burdsall became enthusiastic. He declared 

 that it made clear to his mind chemical facts and laws 

 which he had never before understood. It was cer- 

 tain, he said, that a chart so instructive to him would 

 be equally so to others, and that it would have a large 

 sale if published. He urged Youmans to seek a pub- 

 lisher at once, and offered him five hundred dollars for 

 an interest of one fifth in the enterprise. The advice 

 and offer were promptly accepted, and the cash was 

 applied in getting the chart engraved. Before the 

 engraving was finished the chart was put on exhibi- 

 tion at the American Institute Fair, then held in Castle 

 Garden. Its author prepared a brief primer of ex- 

 planation and tied it to the chart roller, placing his 

 exhibit on a halfway landing of one of the main stair- 

 cases. This chart, when published, was* a great suc- 

 cess. It not only facilitated the acquirement of clear 

 conceptions, but it was suggestive of new ideas. It 

 proved very popular, and kept the field until the 

 binary theory was overthrown by the modern doctrine 

 of substitution, which does not lend itself so readily to 

 graphic treatment. 



The success of the chemical chart led to the writ- 

 ing of a text-book of chemistry. Friends urged that 

 such a book was needed to accompany the chart, and 

 letters began to come in from different parts of the 

 country with a similar request. The idea took root 

 in Youmans's mind, but, as usual, he had more than 

 one task in hand. He devoted part of every day to 

 writing a text-book of arithmetic, wherein the exam- 

 ples were to introduce the constants of science instead 

 of the usual commercial terms. When his work was 



