Some books on classical algebraic geometry I have scanned (they are old and out of copyright):
Federigo Enriques, "Le Superficie Algebriche" (Bologna, 1949) (self scanned)
Henry Baker, Principles of geometry, vol. 6 (Algebraic Surfaces and higher loci) (1933) (self-scanned)
Halphen, Geometry of space curves (Courbes gauches algebriques, fr.) (scanned with help of Michael Friedman)
Some other old books which can be found on the internet, some of them on Archive.org:
J. Semple, L. Roth, Introduction to algebraic geometry (1949)
George Salmon, A treatise on analytic geometry in 3 dimensions (circa 1914) (reprocessed from a file on archive.org)
George Salmon, Higher plane curves (circa 1879) (reprocessed from a file on archive.org)
Blythe, On Models of Cubic Surfaces (1905) (reprocessed from a file on archive.org)
Jessop, C. M., Quartic surfaces with singular points (1916) (reprocessed from a file on archive.org)
Hudson, R. W. H. T., "Kummer's Quartic Surface" (Cambridge, 1905.)
Federigo Enriques, " Lezioni sulla teoria geometrica delle equazioni e delle funzioni algebriche". Bologna, 1915-1934. (published by Oscar Chisini)
(Volume 2/4) (reprocessed from files on archive.org)