Alas, lacking the first, sheet, but still with substantive content and apparently unresearched and unpublished.  The substantial 1.5pp ALS dates to February of 1844 and is from Thomas McCrie [1797-1885] to Robert Shaw. Both were leaders in the Original Secession Church, an earlier iteration of Scottish Presbyterianism opposed to the formal ties between land, political office, and the church that was common in Scotland. 

This was in essence the same cause that led to the Great Disruption of 1843, creating the Free Church of Scotland. This included people like Horatius Bonar, Thomas Chalmers, etc., 

Naturally, a new wave of dissenters, largely Presbyterian in nature, begged the question of union between the Original Secession Church [generally very rigid Calvinists] and the new Free Church, which had a greater diversity of views. The beginning of our letter seems to me to be alluding to the teachings of John McLeod Campbell. While Bonar did not share Mcleod Campbell's views, they had many close relationships and he was not antagonistic toward him. It is too late to be referring to Edward Irving, and called "damnable," so we suspect Campbell is the right referent. 

The text, in full:

"against being understood to favor the New Views in the slightest degree. He condemns their views of faith too, in which point he admires Anderson of America. I urged him to publish something to this effect, & he has agreed to do so. He says too that he knows of none of their ministers, unless it be Bonar of Kelso, who entertains the New Views. You may have seen the last *** Sentinel. There is a very long article in the editorial department against the heresy deeming it as deadly & damnable. Every thing prognosticates to me a struggle which will end in a complete separation of the friends of truth from the abettors of error, - the breaking up of latitudinarian coalitions - & a return I hope to the good old way. But it may take time. From a letter I have received from Dr. 
Symington of Glasgow, I understand that he means to wait republishing his review of Wardlaw till the new Edition of that gentleman's book appears in which he ******* some strictures on Symington. This will probably induce the latter to augment his treatise. The great point however is to get some small tracts, like Bonar's to counteract their principles. I have been thinking of republishing Cole's treatise on Redemption (in his book on Sovereignty) with an Introduction - What do [you] think of this? 

Of course you will be coming in on the 20th. But I should like to hear from you before that. 

Yours very truly.
Thos McCrie

p.s. I may add that Dr. McFarlan, who seemed pretty friendly, saw that all we should do at the first meeting would be to have a little free conversation with each other on the points of difference - & that, if encouraged by this, we could meet more formally afterwards & agree on a report to our respective bodies. He seemed to think it might be as easily go over as the Old Burgher case with the Establishment. 

The main difficulty will be as to terms of communion. I mean the requiring of any test of adherence to *********** from the people. Some plan for this is I believe under contemplation by the F. Church, but they hardly expect their people to be prepared for giving in adherence as we do & some think it wrong to expect it. There is a practical difference among ourselves on this point."