23000 per million, 23 per thousand or one per 4400 (assuming parts are measured by mass)[1] 1. http://www.madsci.org/posts/archives/aug97/868365319.Es.r.html h

23000 per million, 23 per thousand or one per 4400 (assuming parts are measured by mass)[1] 1. http://www.madsci.org/posts/archives/aug97/868365319.Es.r.html http://www.madsci.org/posts/archives/aug97/868365319.Es.r.ht...