MISCELLANEOUS 219 



air absorbs carbon dioxide and again forms sulphate, which 

 being soluble, exerts its fungicidal action — 



4CUO.SO3 + 3OO2 = SCuCOj + CuSO,. 



Other copper preparations used as fungicides are : 



Eau Celeste^ ammonio-copper sulphate, CuS0^.4NH3.H20, 

 made by adding ammonia to a solution of copper sulphate. 

 This yields a magnificent blue solution. The usual proportions 

 are copper sulphate 5 lb., aminonia (strong) 6 or 7 pints, 

 water lOO gallons. 



Ammoniacal Copper Carbonate, made by dissolving 10 ounces 

 of copper carbonate in about 6 pints of strong ammonia and 

 diluting to 100 gallons with water. A deep blue solution. 



In the latter two preparations the copper is in solution, and 

 the liquids have the advantage of not discolouring the fruit and 

 foliage so much as Bordeaux mixture. 



Mei'curic cJdoride, HgClj, "corrosive sublimate," is an 

 extremely powerful poison both to animals and plants. It 

 has been used as a fungicide against bunt in wheat, and 

 for other purposes. A very dilute, solution suffices — ^about 

 1 lb. in 50 gallons of water. Its violent poisonous qualities 

 render it necessary to take every precaution in dealing with 

 this substance. 



Formaldehyde, H,CO, used in the form of a solution in 

 water, ** formalin," containing about 40 per cent, of the real 

 substance. It is an excellent fungicide and disinfectant, and 

 is being more and more used j but as it is also a violent poison 

 to plants it has to be used with care. 



A solution containing 01 per cent, of the real substance — 

 i.e., about 1 quart of formalin to 100 gallons of water — has been 

 recommended as effective for destroying fungi and their spores 

 on grain, clover seed, &c. An hour's immersion of the seed in 

 this solution is recommended. As a preventative of scab in 

 potatoes, immersion of the "sets" for an hour in a solution 

 containing 1 pint of formalin in 30 gallons of water is said to 



