18 Mr. P. H. Gosse on Artificial Sea Water, 



A glance at my paper will show that I gave Dr. Schweitzer's 

 analysis exactly as now given by Mr. Warington ; but, as I wrote 

 for practical people, to whom minute accuracy is impossible, and 

 to whom a chemical formula expressed in quantities of four or 

 five decimals would certainly act as a prohibition, I reduced it 

 to a simpler form ; having first made the experiment, whether 

 such a departure from exact accuracy would vitiate the com- 

 position. 



Now surely here is the point. If I had merely theorized ; — 

 if I had given it as my opinion and nothing more, that the 

 simplified formula would answer, I should be justly blameable ; 

 but I proved my hypothesis before I published it. 



That Mr. Warington's calculations are correct I do not at all 

 deny ; but that they convict mine of '^ error '' I by no means 

 admit; as my facts will presently show. The "error" (which is 

 of that kind technically called " nidtis equce ") lies altogether on 

 the other side. 



The half-gallon of artificial sea-water which was the result of 

 my first experiment, and formed the subject of my communi- 

 cation to your pages, still exists. From the 21st of April to the 

 present date it has never been even shifted from the vessel into 

 which it was first put, nor have its constituents been changed in 

 any respect. 



Now mark the result. A large number of little healthy 

 plants of Ulva and of Conferva have sprung up and grown in it, 

 which on every sunny day give forth a copious supply of oxygen. 

 Some of the original animals yet remain, in a healthful condi- 

 tion, as Actinim and Serpulce ; though others have died off" in the 

 course of the summer, and have been replaced by more. A 

 whole generation of Bowerbankim appeared in August, quite un- 

 expectedly, spreading in ramose shrubs about the glass sides, 

 and after a while died away. At present there are in the vessel, 

 besides those above-mentioned, a Prawn, and several Periwinkles. 

 The water has always maintained, up to this day, a perfect clear- 

 ness. Is not this case conclusive ? 



But I have further evidence. On the 23rd of August last I 

 manufactured nine gallons of sea-water, using the very same 

 proportions of salts as before ; — with which 1 half-filled a square 

 glass tank. 1 stocked it immediately with plants, and in about 

 a week with animals. This experiment also has been perfectly 

 successful. The animals remain in high health to the present 

 time, as do also many more which were added to the stock in the 

 early part of November. Here too the water continues perfectly 

 transparent and colourless. 



The stock of this tank includes at present the following 

 animals : — 



