Candidates' party affiliations obtained from the 11/3/1886 Sacramento Daily Record-Union. https://chroniclingamerica.loc.gov/lccn/sn82014381/1886-11-03/ed-1/seq-3/
The Sacramento Daily Record-Union mentions a fifth candidate, John Weil, running on the Union Labor ticket. Given the large number of Scattering votes listed in the Statement of Vote, it's probable that many of these were in fact Union Labor votes. However, the Statement of Vote has no mention of Weil as a candidate for Treasurer.
Source for Popular Vote data: California Secretary of State. Statement of the Vote of the State of California at the General Election Held November 2, A.D. 1886, California Secretary of State (https://archive.org/details/statementofvoteo1886cali/page/n39/mode/2up?view=theater) (accessed 18 Dec 2023)