THE HAMILTON ASSOCIATION. 55 



between the sulphuric acid and the constituents of bleaching pow- 

 der, and these reactions are represented as follows : That of sul- 

 phuric acid on calcic chloride by the equation Ca CI2 + Ho SOi = 

 Ca SO4 + 2HCI, and that on calcic hypochlorite by the equation 

 Ca (C10)2 + HoSO, = Ca S0,+ 2HC10. Calcic sulphate is one of 

 the products of each reaction, while the other product in the first 

 case is hydrochloric acid, and in the second case is hypochlorous 

 acid. This last material is very unstable, and is consequently readily 

 acted upon by the hydrochloric acid, producing a result which is 

 represented by the equation H C1 + HC10 = H0O + CI2; or we may 

 represent the complete reaction by one equation, which will cover 

 the ground of the other three, viz : Ca Clg + Ca (C10)2+ 2H2S04 = 

 2Ca S04+2H2O + sClg. We thus see that if the material to be 

 bleached be immersed in an aqueous solution of the powder, or an 

 aqueous solution which is afterwards acidulated, it will be brought 

 in contact with the chlorine which is to effect the bleaching. 



Without further experiment it is impossible to say what part 

 the chlorine takes in the process. A few simple experiments will 

 assist us in deciding the question. If a piece of colored calico, 

 which has been well dried, be placed in a jar of chlorine from which 

 the moisture has been removed by passing the gas over chloride of 

 lime contained in tubes, and allowed to remain there for any length 

 of time, it will be found that the color is not materially affected, but 

 if the cloth be removed, moistened and returned to the jar, the 

 color will in a short time disappear. Evidently then the water plays 

 an important part in the process of bleaching by means of chlorine. 



In this flask there remains material from an experiment which 

 has been going on for several days. When the apparatus of this ex- 

 periment was set up, the flask was completely filled with a solution 

 of chlorine in water ; the glass tube inserted in the cork is drawn out 

 to a fine point, so that the liquid cannot fall out of its own weight ; 

 the whole was then exposed to sunlight for a number of days, with 

 one evident result at least, namely, the formation of a large bubble 

 of gas in the upper end of the flask. In this tube there is a solution 

 of chlorine similar to that which was placed in the flask and exposed 

 to the sunhght. Let us add a few drops of this solution to a solu- 

 tion of blue litmus : you observe the color is completely destroyed. 

 In this tube there is a solution similar to that now contained in the 

 flask ; add some of it to some blue litmus solution and it becomes 



