Search Engine may know about visits to orphaned (i.e. no inbound links) websites based on users who may have a toolbar installed that is reporting browsing activity back to the search engine. Whether this is used as a ranking signal is debatable.

Also if you use a tool such as Google Analytics then Google in this case will certainly know a great deal about your website users. Again it's very unlikely that they will be using this as any basis to rank your site, which I think is at the crux of your question.

Inbound links and good content pretty much cover 90% of the ranking outcome for any website. Nothing has changed there for years!

Does the number of visits matters for SEO?
During the electrolytic purification of copper, the electrolyte is taken as copper(II) sulphate ($\ce{CuSO_4}$). Is there any particular reason for this? Could another salt of copper, say $\ce{CuCl_2}$ work?

I mean, I don't see any reason why it shouldn't. The only difference will be, that at the anode chlorine instead of oxygen will be evolved, which doesn't seem to be such a big thing. 

Why, then, is $\ce{CuSO_4}$ preferred?  
