76 



ent periods of time, well washed in water, and weighed. 

 They were then heated in a kitchen oven and again weighed. 

 The results are given in the table below. 



TABLE SHOWINa THE INCREASE OF WEiaHT AFTER IMMERSION 



IN ACID. 



HYDROCHLORIC ACID. 



SULPHURIC ACID. 



In all cases except one they were found to have lost in 

 weight, and the exception was probably owing to the 

 increased weight caused by a slight coating of oxide over- 

 balancing the loss occasioned by heating. 



