FURR. 263 



and mineral salt, separated from the 

 water by the process of boiling. 



Q. Is not this FURR of boiling water often 



DANGEROUS? 



A. Yes; especially in tubular 

 boilers, such as those employed in 

 railways. 



Q. Why is this FURR especially TROUBLESOME 

 in RAILWAY engines ? 



A. Because it is a bad conductor of 

 heat ; in consequence of which, it 

 hinders the evaporating effect of the 

 fire, and prevents the economy of fuel. 



Q. Why is this FURR especially DANGEROUS 

 in RAILWAY engines ? 



A. Because when it is deposited in 

 the boilers, they are likely to become 

 over -heated ; and then explosion will 

 take place from the sudden generation 

 of highly elastic steam. 



Q. Why cannot RAILWAY engines be fed with 



BRACKISH WATEE ? 



A. Because brackish water contains 

 mineral salt, which makes a much 

 larger deposit of furr, than that which 

 contains only vegetable matter. 



