512 Reed . — The Value of Certain Nutritive Elements 
taining 1,500 cc. of redistilled water, and shaken for several minutes. The 
bottle was allowed to stand until most of the ferric hydroxide had settled 
to the. bottom, then the supernatant water was passed through a filter paper 
and used for making up solutions. 1 
When stock solutions were necessarily kept for some length of time, 
they were stored in flasks of Jena glass closed with rubber stoppers. Where 
I desired to cultivate plants in the absence of potassium, the glass-ware to 
be used for the cultures was filled with a solution of potassium hydroxide. 
After standing for several weeks, the glass-ware was thoroughly washed out 
with water, and steamed for several hours in an Arnold sterilizer. By 
means of this treatment it is believed that the error of experiment due to 
soluble bases in the glass was reduced, but not entirely eliminated. It has 
been shown by Kohn (’05) and Benecke (’07) that the growth and pigment 
formation of certain bacteria is influenced by small amounts of the essential 
elements contained in the glass. It need not be assumed, however, that 
the growth of algae or of phanerogams would be as greatly influenced by 
the presence of these salts, as bacteria have been shown to be. I tried to 
use vessels lined with a coating of paraffin as described by Molisch (’95)) 
but without success. The paraffin contained petroleum products which had 
a toxic effect upon the plants. 
The solutions for experiments were prepared by mixing proper quantities 
of the stock solutions, and diluting to the proper concentration. 
1 My experiments with water prepared in this manner confirm the experience of Livingston (’07) 
that such distilled water gives a superior growth of plants when used as the basis for a culture 
solution. These results are in harmony with the work of Lyon (’04) in which he found that tap- 
water which was decidedly toxic to Arbacia eggs was much improved by boiling away one-third of 
its volume. When the water was distilled from glass into glass the first, second, and third tenths of 
the distillate exhibited toxic properties, the fourth portion was of good quality. The best quality 
of distilled water was obtained by distilling in glass with potassium bichromate and sulphuric acid 
added to the contents of the retort. A theory has recently been propounded by Schreiner and the 
writer (’07) to explain the toxic properties of some distilled waters. It has been shown that even 
when distilled in glass apparatus many soil extracts give water unsuitable for the growth of plants- 
This is probably due to the existence of toxic substances in the soil extract which are volatile and 
pass over with the water vapour. These toxic substances may often be boiled off with resulting 
improvement to the soil extract. All waters from wells, springs, rivers, or lakes are virtually soil 
extracts. Upon distillation the volatile toxic substances may pass over with the steam, are condensed, 
and appear in the distillate. It is true that repeated distillation in the presence of active oxidizing 
or reducing agents will remove such substances, but they are more easily and innocuously removed by 
treatment with an absorbing agent like ferric hydroxide. Rain-water gathered in glass vessels is not 
toxic to plants. This good quality is to be accounted for by the fact that such water remains for 
some time in the vapour condition, and as such is subjected to the action of air, light, and other agents 
capable of effecting oxidation. The action of these agents is probably the same as that of the 
oxidizing agents added to the retort of the distilling apparatus. 
