Apologetic apostrophe

The 'apologetic' or parochial apostrophe is the distinctive use of apostrophes in Modern Scots orthography. Apologetic apostrophes generally occurred where a consonant exists in the Standard English cognate, as in ' (all), ' (give) and "" (with).
The practice, unknown in Older Scots, was introduced in the 18th century by writers such as Allan Ramsay, Robert Fergusson and Robert Burns as part of a process of Anglicisation. The 18th-century practice was also adopted by later writers such as Walter Scott, John Galt and Robert Louis Stevenson. It produced an easily understood spurious Scots that was very popular with English readers and on the English stage. It was also sometimes forced on reluctant authors by publishers desirous of a wider circulation for their books.
The custom "also had the unfortunate effect of suggesting that Broad Scots was not a separate language system, but rather a divergent or inferior form of English". The use of the apologetic apostrophe became less widespread after the appearance of the 'Style Sheet' in 1947 and is now considered unacceptable, the apostrophe-less forms such as ' (all), ' (give) and "" (with) being preferable.
L-vocalisation.
Early Scots had undergone a process of L-vocalisation where /l/ was preceded by the vowels and in closed syllables, which was completed by the end of the 14th century. The cluster vocalised to and to hence spellings such as "a" (all), "ba" (ball), "ca" (call), "sa't" (salt) and "ha'd" (hold), and "fu" and "pu" with the doublets "full" and "pull" . The standard literary apostrophe-less spellings for (also ) were and with generally occurring word initially or medially, and occurring word final thus "aw" (all), "baw" (ball), "caw" (call), "saut" (salt) and "haud" (hold).
The standard literary spelling of was , generally preferred in the "Scottish National Dictionary", although the use of , borrowed from Standard English, became popular by the 19th century. Thus "fou" and "pou", but the form "fu" functioning as the cognate of the suffix 'ful'. L also vocalised after in closed syllables resulting in a diphthong which became in Modern Scots, for example "knowe" (knoll), "fowk" (folk), "gowf" (golf) and "gowd" (gold).
Inflectional endings.
The consonant clusters in the inflectional endings and , cognate with Standard English , changed to in Early Scots: the modern realisations generally being and hence the spelling "in".
Consonant clusters.
The cluster had been reduced to in Early Scots hence spelling such as "num'er" (number), "cham'er" (chamber) and "tim'er" (timber), the standard literary apostrophe-less spellings being "nummer", "chaumer" and "timmer".
The cluster is reduced to in some Scots dialects hence spellings such as "caun'le" (candle), "haun" (hand) and "staun" (stand) though the is generally written in the literary standard, thus "caundle", "haund" and "staund".
The cluster is also reduced to in some Scots dialects, hence spellings such as "aul" (old), "caul" (cold) and "faul" (fold) though the is generally written in the literary standard, thus "auld", "cauld" and "fauld".
Loss of consonants.
By the Middle Scots period, and deletion had occurred intervocalically and between a nasal/liquid consonant and a vowel. Hence spellings such as "de'il" (devil), "gi'e" (give), "ha'e" (have), "lo'e" (love), "o" (of), "o'er" (over) and "sil'er" (silver), the standard literary apostrophe-less spellings being "deil", "gie", "hae", "lue", "o", "ower" and "siller".
Also by that period, word-final had been lost in a number of words. Hence spellings such as "fro'" (froth), "quo'" (quoth), "wi'" (with) and "mou"' (mouth), the standard literary apostrophe-less spellings being "fro", "quo", "wi" and "mou", the latter having the doublet "mooth".
Change of vowel.
In some Scots words the realisation differs from that of the Standard English cognate; hence spellings such as "bak" (bake), "mak" (make) and "tak" (take), the standard literary apostrophe-less spellings being "bak", "mak" and "tak".
Legitimate use of the apostrophe in Scots.
Many words in Scots have both a full form and a contracted form. In contracted forms, an apostrophe is generally used in place of the elided graphemes, for example, "e'en" and "even", "e'er" and "iver" (ever), "eneu" and "eneuch" (enough), "lea" and "leave", "ne'er" and "niver" (never), "ne'er's day" and "new year's day", "nor'land" and "northland".
In the construction of the past tense or past participle, Scots often appends the apostrophe to verbs ending with "ee" to prevent three "e"s from occurring in a single word:
Scots also uses, as does English, the apostrophe to indicate contractions of multiple words: "A'm" (I'm), "wi't" (with it), "ye're" (you're), "o't" (of it).