One volume of something

I am following some protocols for a reaction and after diluting my substrate in a solution I need to precipitate it in methanol. 
For this I need to pour my solution into "one volume" of methanol- 


What I do not understand is what is meant by 'one volume'. Is a measurement of quantity. 


The protocol can be found under the *Sulfation of cellulose* part of the methods section in:
R. G. Schweiger, “Polysaccharide sulfates. I. cellulose sulfate with a high degree of substitution,” Carbohydr. Res., vol. 21, 219–228, 1972 ([DOI: 10.1016/S0008-6215(00)82148-5](http://www.sciencedirect.com/science/article/pii/S0008621500821485)).




If the reaction till "then" was a solution of, say 500 mL, than the addition of the next liquid – from your writing, it reads like it were methanol – should be equally just 500 mL. (And 500 divided by 500 were ... just 1).


Maybe adding *more* than one part of methanol would no longer lead to (this much / this clean) precipitation intended, as methanol alone is quite a good solvent of your precipitate\*), too.


\*) Intentionally leaving open, if the precipitate is an impurity to be removed, or really refers to the product *to be isolated*. You have the literature reference.


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