IN CHEMISTRY. Ill 



4. What weight of NaCl would be required to form 25 

 Ibs. of muriatic acid ? 



(See Key^ page 58, Question 20.) 



5. HC1 of a specific gravity of 1.2 contains about ^ per 

 cent, of the gas. This is very strong commercial acid. 



What weight could be formed by the HC1 acid gas produced 

 in the reaction named in the preceding problem ? 



(See Key, page 58, Question 21.) 



6. What is the difference between sublimation and distilla- 

 tion ? 



A body is said to sublime when it rises as vapor and 

 condenses in the solid form ; when it condenses as a liquid 

 it is said to distil. 



7. Why do eggs discolor silver spoons ? 



The sulphur of the egg combines with the Ag, forming 

 silver sulphide the black sulphuret of silver. 



8. Explain the principle of hair-dyes. 



The two principal chemicals used for dyeing the hair are 

 lead and silver nitrate. The S in the hair combining with 

 the Ag makes silver sulphide, or with the Pb, lead sul- 

 phide, either of which stains the hair : the former colors 

 the skin as well as the hair, while the latter is absorbed 

 through the skin, causing colics and other diseases such 

 as are common among painters. The "golden yellow 

 color" lately in fashion is produced by a solution of ar- 

 senic with the hydrosulphate of ammonia. In order to 

 dye the lighter tints, it is necessary to bleach the hair 

 with an alkaline solution. See Fireside Science, page 77. 



