the boss one can power more than one boss pedal with a dc chain(more commonly refered to as daisy chain), provided that all the current drawn value in miliAmpere across all the pedals add up together, is lower than what the power adaptor has to offer.
the rating of the adaptor is usually indicated on the power adaptor itself. From the picture below, note the rating, pri is primary source(230volt AC, which is what the adaptor is receiving from the electrical outlet in our home. Sec is secondary, which is the output of the adaptor thats fed to the pedals, at 9volt DC, 200miliampere rating. 200mA is the total current value available to the effect pedal.
For boss pedal and most of the mass produced pedals, 9vdc rating is pretty much a standard rating, the difference will be in the current drawn value which, for most boss deal are in the region of single digit mA rating to double digit mA rating.
All pedals will only draw whats needed for the operation. As long as the total amount of current drawn value across all the pedals sharing the dc chain(with 1 adaptor), is lower than the 200mA rating of the adaptor, there should not be any problem. Problem comes in the form of damaged power adaptor when all the pedals in the chain are drawing more then 200mA, which the adaptor cannot cope and overwork to its death, burnt smell included. I did try many many years ago using 2 daisy chain with one boss adaptor to power 8 boss pedals, it works, but the adaptor quite hot after a while, so didnt really test the limit of how long it can last.
Another thing to look at, is the logo of the adaptor barrel with positive and negative sign. That one, also much match the adaptor and pedal power jack. Again, for boss pedal and most common pedals, its always needing a center negative supply.
For more power topics, go here,
http://stinkfoot.se/power-list
http://stinkfoot.se/articles/power