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the vitriol works at Prestonpans。 At the same time； he transferred to
Mr。 Boulton of Soho his entire interest in Watt's steam…engine； the
value of which； by the way； was thought so small that it was not even
included among the assets； Roebuck's creditors not estimating it as
worth one farthing。 Watt sincerely deplored his partner's
misfortunes； but could not help him。 〃He has been a most sincere and
generous friend；〃 said Watt； 〃and is a truly worthy man。〃 And again；
〃My heart bleeds for him； but I can do nothing to help him： I have
stuck by him till I have much hurt myself； I can do so no longer； my
family calls for my care to provide for them。〃 The later years of Dr。
Roebuck's life were spent in comparative obscurity； and he died in
1794； in his 76th year。
He lived to witness the success of the steam…engine； the opening up
of the Boroughstoness coal；*
＇footnote。。。
Dr。 Roebuck had been on the brink of great good fortune； but he did
not know it。 Mr。 Ralph Moore； in his 〃Papers on the Blackband
Ironstones〃 （Glasgow； 1861）； observes： 〃Strange to say； he was
leaving behind him； almost as the roof of one of the seams of coal
which he worked； a valuable blackband ironstone； upon which Kinneil
Iron Works are now founded。 The coal…field continued to be worked
until the accidental discovery of the blackband about 1845。 The old
coal…pits are now used for working the ironstone。〃
。。。＇
and the rapid extension of the Scotch iron trade； though he shared in
the prosperity of neither of those branches of industry。 He had been
working ahead of his age； and he suffered for it。 He fell in the
breach at the critical moment； and more fortunate men marched over
his body into the fortress which his enterprise and valour had mainly
contributed to win。 Before his great undertaking of the Carron Works；
Scotland was entirely dependent upon other countries for its supply
of iron。 In 1760； the first year of its operations； the whole produce
was 1500 tons。 In course of time other iron works were erected； at
Clyde Cleugh； Muirkirk； and Devonthe managers and overseers of
which； as well as the workmen； had mostly received their training and
experience at Carronuntil at length the iron trade of Scotland has
assumed such a magnitude that its manufacturers are enabled to export
to England and other countries upwards of 500；000 tons a…year。 How
different this state of things from the time when raids were made
across the Border for the purpose of obtaining a store of iron
plunder to be carried back into Scotland！
The extraordinary expansion of the Scotch iron trade of late years
has been mainly due to the discovery by David Mushet of the Black
Band ironstone in 1801； and the invention of the Hot Blast by James
Beaumont Neilson in 1828。 David Mushet was born at Dalkeith； near
Edinburgh； in 1772。*
＇footnpote。。。
The Mushets are an old Kincardine family； but they were almost
extinguished by the plague in the reign of Charles the Second。 Their
numbers were then reduced to two； one of whom remained at Kincardine；
and the other； a clergyman； the Rev。 George Mushet ； accompanied
Montrose as chaplain。 He is buried in Kincardine churchyard。
。。。＇
Like other members of his family he was brought up to metal…founding。
At the age of nineteen he joined the staff of the Clyde Iron Works；
near Glasgow； at a time when the Company had only two blast…furnaces
at work。 The office of accountant； which he held； precluded him from
taking any part in the manufacturing operations of the concern。 But
being of a speculative and ingenious turn of mind； the remarkable
conversions which iron underwent in the process of manufacture very
shortly began to occupy his attention。 The subject was much discussed
by the young men about the works； and they frequently had occasion to
refer to Foureroy's well…known book for the purpose of determining
various questions of difference which arose among them in the course
of their inquiries。 The book was； however； in many respects
indecisive and unsatisfactory； and； in 1793； when a reduction took
place in the Company's staff； and David Mushet was left nearly the
sole occupant of the office； he determined to study the subject for
himself experimentally； and in the first place to acquire a thorough
knowledge of assaying； as the true key to the whole art of
iron…making。
He first set up his crucible upon the bridge of the reverberatory
furnace used for melting pig…iron； and filled it with a mixture
carefully compounded according to the formula of the books； but；
notwithstanding the shelter of a brick； placed before it to break the
action of the flame； the crucible generally split in two； and not
unfrequently melted and disappeared altogether。 To obtain better
results if possible； he next had recourse to the ordinary smith's
fire； carrying on his experiments in the evenings after office…hours。
He set his crucible upon the fire on a piece of fire brick； opposite
the nozzle of the bellows； covering the whole with coke； and then
exciting the flame by blowing。 This mode of operating produced
somewhat better results； but still neither the iron nor the cinder
obtained resembled the pig or scoria of the blast…furnace； which it
was his ambition to imitate。 From the irregularity of the results；
and the frequent failure of the crucibles； he came to the conclusion
that either his furnace； or his mode of fluxing； was in fault； and he
looked about him for a more convenient means of pursuing his
experiments。 A small square furnace had been erected in the works for
the purpose of heating the rivets used for the repair of steam…engine
boilers； the furnace had for its chimney a cast…iron pipe six or
seven inches in diameter and nine feet long。 After a few trials with
it； he raised the heat to such an extent that the lower end of the
pipe was melted off； without producing any very satisfactory results
on the experimental crucible； and his operations were again brought
to a standstill。 A chimney of brick having been substituted for the
cast…iron pipe； he was； however； enabled to proceed with his trials。
He continued to pursue his experiments in assaying for about two
years； during which he had been working entirely after the methods
described in books； but； feeling the results still unsatisfactory； he
determined to borrow no more from the books； but to work out a system
of his own； which should ensure results similar to those produced at
the blast…furnace。 This he eventually succeeded in effecting by
numerous experiments performed in the night； as his time was fully
occupied by his office…duties during the day。 At length these patient
experiments bore their due fruits。 David Mushet became the most
skilled assayer at the works； and when a difficulty occurred in
smelting a quantity of new ironstone which had been contracted for；
the manager himself resorted to the bookkeeper for advice and
information； and the skill