OP ARTS AND SCIENCES. 247 



Thickness of one sheet tinfoil 0006Gcm. 



" of paper sheet 014 " 



Areaof tinfoil (12.7 X;iO) 381 sq. cm. 



Capacity calculated for an equal air condenser by Ayrton's formula .1827mfd. 

 Capacity found by comparison with No. 72 (Elliott Bros.) standard 



microfarad condenser 417 nifd. 



Specific inductive capacity 2 28 



Condenser No. 2 was made exactly like No. 1, except that it had 

 106 sheets of paper. 



Condenser No. 3 was made of 104 sheets of paraffined rag paper, 

 of the same size as the sheets in No. 1. 



Condenser No. 4 was made of pulp paper similar to that used by 

 the daily newspapers. It is tedious to make a condenser of this, on 

 account of " leaks " caused by small holes and bits of metal. No. 4 

 has 72 sheets of the same size as those in No. 1. 



Experiments with these three kinds of paraffine paper condensers 

 confirmed the results of the paper tests. No. 3 is by far the best 

 condenser. I concluded, therefore, to use the rag paper in the larger 

 condensers. • 



Nos. 5, 6, 7, and 8 were made of rag paper similar to that of No. 3, 

 and of the same lot of paraffine. 



Dimensions of Nos. 5 to 8. 



Effective area of tinfoil 12.6 X 35 cm 441 sq. cm. 



Taking the specific inductive capacity as found, 2.28, we should require 67,437 

 sq. cm. of tinfoil for one microfarad capacity, or 153 sheets. 



Condensers Nos. 5 and G required 154 sheets each to equal the ca- 

 pacity of the standard microfarad ; No. 7 required 72 sheets to equal 

 0.5 mfd. ; No. 8, intended for a tenth microfarad, contained 16 sheets. 



Condensers Nos. 14, 15, 16, and 17 were made of the same lot of 

 paper used in No. 5, but of harder paraffine. The melting point was 

 determined at 51.5-52° C. No. 14 had 76 sheets ; No. 15, 78 sheets; 

 No. 16, 138 sheets ; and ]^o. 17, 16 sheets. 



Condenser " G," also of paraffine paper, is an old instrument, made 

 in the Jefferson Laboratory, of bond paper. It occupies a large 

 uncovered box, and is held in place by paraffine, which completely 

 surrounds and covers it. 



Condenser No. 18, also of paraffine paper, was similarly protected 

 by paraffine in a covered box. 



I made a condenser of 12 sheets of bond paper soaked in boiled 

 linseed oil. Its capacity appeared to be large, but it had a resistance 



