Gothic script in which letters seem to be all mixed up

Question

This question concerns a text written in what I think is the Gothic script, specifically Lateinische Grammatik by Friederich Ellendt et al., in which letters seem to be used in very strange ways.

It seems to me the fourth line of the body may read:

Von den durch diese Buchstaben bezeichneten Lauten sind Vocale:

If that is right, 'B' seems to do double duty as both 'B' and 'V', and 's' for both 's' and 'c'.

Again the next line may read:

Durch die Verbindung zweier Vocale zu einem Laute entstehen Doppelvocale oder Diphthonge.

If so, 'B' is doing the job of 'V' in 'Verbindung'.

The next paragraph may go:

Die übrigen Laute sind Consonaten.

In which case, 'R' figures as 'C' in 'Consonaten'.

QUESTIONS

Does this represent some rational or once current system of substitution? If so, is there a name for it?

Answer 1

There is no substitution of letters in the text you posted.

You are looking at writing in a blackletter typeface (German: gebrochene Schrift, lit. broken font) possibly Fraktur. What you believe to be c (Vocale) ist in fact k (Vokale), routinely spelled that way in German. The same thing is true for Konsonanten.
Also, pay attention to subtle details: 𝕭 (B) and 𝖁 (V) may very much look alike, but only in 𝕭 do the sides meet in the middle. Further, 𝖋 (f) is distinguished from the long s by a point to the right and there are similar differences between 𝖐 (k), 𝖑 (l) and 𝖙 (t). Try zooming your browser to see more clearly.

German Wikipedia points out the differences in more detail.

Here is as much of the Fraktur alphabet as can be readily found in Unicode (and thus shown on Stack Exchange), i.e. the letters of the Roman alphabet, but lacking long s (ſ), eszet (ß), and letters with umlauts (ä ö ü):

𝔄  𝔅     𝔇  𝔈  𝔉  𝔊        𝔍  𝔎  𝔏  𝔐  𝔑  𝔒  𝔓  𝔔     𝔖  𝔗  𝔘  𝔙  𝔚  𝔛  𝔜
𝕬  𝕭  𝕮  𝕯  𝕰  𝕱  𝕲  𝕳  𝕴  𝕵  𝕶  𝕷  𝕸  𝕹  𝕺  𝕻  𝕼  𝕽  𝕾  𝕿  𝖀  𝖁  𝖂  𝖃  𝖄  𝖅
𝔞   𝔟  𝔠   𝔡  𝔢   𝔣  𝔤   𝔥  𝔦   𝔧   𝔨  𝔩   𝔪  𝔫   𝔬  𝔭  𝔮   𝔯   𝔰  𝔱   𝔲  𝔳  𝔴   𝔵  𝔶   𝔷
𝖆   𝖇  𝖈   𝖉  𝖊   𝖋  𝖌   𝖍  𝖎   𝖏  𝖐  𝖑   𝖒  𝖓   𝖔  𝖕  𝖖   𝖗   𝖘  𝖙   𝖚  𝖛  𝖜   𝖝  𝖞   𝖟

These symbols are in the Unicode block Mathematical Alphanumeric Symbols with codes from 1D504 to 1D537 (plain) and 1D56C to 1d59F (bold); strangely, uppercase 𝕮 (C), 𝕳 (H), 𝕴 (I), 𝕽 (R) and 𝖅 (Z) are only available in bold, though the spaces for them are reserved as unassigned in the plain version.