Thermometer used by Professor Joseph Black

There is no certainty that this thermometer has anything to do with Black, other than a reported comment made by Matthew Forster Heddle of St Andrews in 1869, some 70 years after Black's death (see R G W Anderson 'The Playfair Collection...' (1978) p.158 - for some reason not given in the reference section, even though published by the RSM). If it is accepted that the thermometer does have a Black connection, why limit the date to 1790, as Black taught up to the 1795/96 session? Other points: what does the expression "quantitative chemical analysis of the processes of boiling, melting..." mean? Why is the date of publication of the Black bibliography given as c.1992? (it WAS 1992). It would be useful to know what the instrument's scale is.