122 MARINE AQUARIA ^^^^^^^^^^^^,,,= 



varnish. Even galvanized iron when asphaltum-coated is safe for 

 journe3's of moderate length, but the asphaltum will eventually chip 

 ofif and the pail or can should be carefully looked over each time be- 

 fore using. It might be well to say here that the life of tin pails for 

 any water will last much longer if coated with asphaltum varnish. A 

 thin coat spread evenly lasts better than a thick one. 



The very best water-shipping medium is a protected glass bottle or 

 carboy. Arrangements can usually be made to rent or borrow a few of 

 these from drinking-water concerns. If possible the water should be 

 taken from several miles out at sea and not near the mouth of any large 

 river. Clear seawater may be stored indefinitely in carboys in a subdued 

 light, although it would be better to first filter it to remove the larger 

 microscopic life. 



Artificial Seawater. Experience varies regarding the use of artificial 

 seawater. This may be due to difference in the degree of purity of chem- 

 icals used or care in their mixing. The author has not been particularly 

 successful with artificial marine water, although some writers claim it to 

 be better than ocean water because of its freedom from impurities and 

 marine bacteria. The following is a correct working formula for artificial 

 seawater. There are other elements in the ocean, but in such small 

 quantities as to be negligible for our purposes : 



Sodium chloride (Tablesalt) . . .2 lb. 8.> 23. 18 gr. 



Magnesium chloride 3,5- 53. 13 gr. 



Magnesium sulphate 2.5. 33. \'S 8 gr. 



Potassium sulphate 53. 29 10 gr. 



and sufficient wellwater to bring the whole to ten gallons. 

 These proportions of salts, expressed in the Metric system, would be: 



Sodium chloride 663 grams. 



Magnesium chloride 75 " 



Magnesium sulphate 50 " 



Potassium sulphate 15 " 



Added to 25 litres of wellwater. 

 For chemical reasons the salts should each be dissolved separately 

 and enough water finally added to make ten gallons. Any good drinking 

 water will do to mix with, although distilled water is not to be recom- 

 mended because of its total lack of mineral content. Turk's Island salt 

 is evaporated seawater and has been successfully used by the Government 

 at Washington, although reports from other authorities are not so 

 favorable. In mixing this or in preparing the foregoing artificial 

 water, the final test for strength should be by hydrometer as previously 

 directed. As chemicals vary in strength and in weight owing to different 

 degrees of moisture, the hydrometer used in solutions of about 60° 

 Fahrenheit furnishes the only accurate gauge. 



