Handel spent more than three years in Italy, not long before his relocation to London. His 1760 biographer Mainwaring's famous story about Scarlatti's supposed "the famous Saxon or the devil", is (as Kirkpatrick points out) "a perennial legend in connection with well-known musicians, and its context is notably inaccurate". Possibly the legend arose as the result of an even more amusing incident which has since come to light. According to Denis Nolhac, a French Huguenot from Germany visiting Rome, at a reception given by the Pope's musicians early in 1707 Handel sat down to play the harpsichord with his hat still under his arm, and the Italians (knowing him to be a Lutheran) started to imagine some kind of diabolical pact possibly involving the hat. Nolhac, overhearing their talk, quietly informed him of this (in German, so as not to be understood generally). Without stopping Handel proceeded 'accidentally' to drop the hat and, hardly surprisingly played even better than before.
It was Cardinal Ottoboni who seems to have arranged a trial of skill between the two, and from this point (according to Mainwaring) Scarlatti "followed him all over Italy, and was never so happy as when he was with him". It would be surprising if the two had not kept in touch, especially as it's now known that the Essercizi were published in London (not Venice as previously thought) in 1738, closely followed by Roseingrave's edition. Roseingrave was a friend of Scarlatti (his visit to Italy overlapped Handel's), and it seems unlikely that he would have published without the latter's approval. There is also the question of Roseingrave's source(s) for the dozen sonatas his edition adds to the thirty found in the Essercizi. Some are from Scarlatti's most up-to-date output, others clearly much older.
Among these last is K35, a sonata I've felt for many years to have a resonance with Handel (I've since noticed Kirkpatrick makes the connection, though in much more general terms). But it was only a few years ago I found myself wondering why Handel had written such a curious piece as the so-called "Capriccio" in G minor HWV483, quite out of his usual character. It began to dawn on me that there seemed to be elements of gentle parody -- for example, the sudden lurch from C to D minors with the entrance of the left-hand at bar 5. Particularly Scarlattian are the enharmonic broken arpeggios just before the ending (c.f. K460 bb22ff & 120ff), and of course the (here persistent) use of diminished harmony. Both pieces share the same key and the same 4/4 time signature. Even more extraordinarily, both pieces close with the same group of eight notes (in the case of Scarlatti' binary piece twice, although in the second half he reverses the last two)!
As examples of Scarlatti's style, here are two other sonatas from the Roseingrave collection (the opening bars of K33 supplied by another
source). Although unlikely to have been intended as a pair, the two work well together:
K32 & 33 download mp3 (4.9 Mb)
And now, K35 "Scarlatti in the style of Handel": download mp3 (2.4 Mb)
And, HWV483 "Handel in the style of Scarlatti": download mp3 (2.1 Mb)