[susan53]

I was curious about your first question so I went and looked up Johnson's Preface. I suspect the example you are referring to is this :

Our knowledge of the northern literature is so scanty, that of words undoubtedly Teutonick the original is not always to be found in any ancient language; and I have therefore inserted Dutch or German substitutes, which I consider not as radical but parallel, not as the parents, but sisters of the English.

Notice that here English is not the noun but an adjective. The full noun phrase is :
... but sisters of the English word.
word is ellipted in the original sentence, because retrievable from context (though the archaic quality of the text, with its tendency to sentences much longer than is currently normal, makes this more difficult for us now than it would be with a more modern sentence). But if you put the word back in, the grammar is clear.