394 SCIENCE IN SHORT CHAPTERS. 



injected with sulphate of copper, in order to avert infec- 

 tion, and in support of this refers to the immunity of 

 workers in copper from cholera, typhoid fever, and infec- 

 tious diseases generally. 



I agree with him to the extent of suggesting the desira- 

 bility of occasionally mopping house floors with this solu- 

 tion. Its visible effects on the wood are first to stain it 

 with a faint green tinge which gradually tones down to a 

 brown stain, giving to deal the appearance of oak, a change 

 which has no disadvantage from an artistic point of view. 

 If the wood is already tainted with organic matter capable 

 of giving off sulphurated hydrogen, the darkening change 

 is more rapid and decided, owing to the formation of sul- 

 phide of copper. 



The solution of sulphate should not be put into iron or 

 zinc vessels, as it rapidly corrodes them, and deposits a 

 non-adherent film of copper. It will even disintegrate com- 

 mon earthenware, by penetrating the glaze, and crystalliz- 

 ing within the pores of the ware, but this is a work of time 

 (weeks or months). Stoneware resists this, and wooden 

 buckets may be used safely. It is better to keep the crys- 

 tals and dissolve when required. Ordinary earthenware 

 may be used with impunity if washed immediately after- 

 wards. 



ENSILAGE. 



This subject has been largely expounded and discussed 

 lately in the Times and other newspapers. As most of my 

 readers are doubtless aware, it is simply a substitute for 

 haymaking, by digging pits, paving and building them 

 round with stone or concrete, then placing the green fod- 

 der therein and covering it over with sufficient earth to 

 exclude the air. 



We are told that very inferior material (such as coarse 

 maize grass mixed with chaff) when thus preserved gives 

 better feeding and milking results than good English hay. 



I may mention a yery humble experience of my own 



