388 Messrs. Wright and Thompson on the Determination of 



meter ; the contraction was then calculated by means of the 

 formula 



W + w 



IV 



w 



Cz= V 1 + -998602 



where C is the contraction in cubic centimetres, 



W the weight (in vacuo) of solution diluted, 



w j, ,, of the water added thereto, 



Si the weight at 18°*5 of 1 cubic centim. of the solution 



diluted, 

 s 2 the weight at 18 0, 5 of 1 cubic centim. of the dilute 

 fluid produced. 



The following numbers will serve as an example : — 



Tempera- 

 ture. 



Dilatometer 

 reading. 



Reading at 



18°-5. 



Cubic centim. 



corresponding 



from table of 



instrument. 



Weight of 

 fluid in 

 vacuo. 



"Weight in 



vacuo of 1 cubic 



centim. at 



18°-5* 



17-0 

 197 

 170 

 19-3 



6-25 

 7-70 

 1-15 

 225 



| 705 



| 1-87 



94743 

 94-556 



97-671 

 97-467 



1-03090 

 1-03088 



Mean 1*03089 



This solution was made by mixing 53*781 grammes of 

 copper-sulphate solution (of which one cubic centim. was 

 similarly found to weigh 1' 18725 gramme) with 232*509 

 grammes of water (all weights corrected to vacuum), whence 



p _ 53*781 232*509 



1*18725 + -998602 ^ r03089 



286 'S!? -422. 



* In the course of these observations the following mean numbers 

 were obtained, representing the weights in vacuo at 18°'5 C. of 1 cubic 

 centim. of various solutions MS0 4 wH 2 0: — 



Copper sulphate. 



Zinc 



sulphate. 



Cadmium sulphate. 



n=US 1*18725 



n=-- 19-06 



1-41699 



n= 1581 



1-59169 



75-3 1-11325 



19-31 



1-41073 



18-07 



1-52829 



109-9 1078155 



21-33 



1-376055 



18-10 



1-52724 



174-9 1-049195 



32-3 



1-25859 



32-4 



1-31285 



276-4 1-03089 



495 



1-17310 



49-4 



1-21020 



462-7 1-01805 



98-8 



1-088265 



95-6 



1-11082 





1428 



1-061275 



162-9 



1-06537 





219-1 



1-03980 



2604 



1-040795 





4221 



1-020215 



424-4 



1-02461 





466-0 



1-01817 







