Hg (I) salts (mercurous) are less soluable in H2O than mercuric (II) salts, and less bioavailable as such. Mercurous chloride, or calomel, as it used to be known in medical practise was often used as a laxative, or emetic, and as a component of teething powders for babies(!) and by the 1800s was recognised as less toxic than Hg (II) chloride, known then as corrosive sublimate was well known to be a virulent poison, although still used as a purgative, stuff was even injected as a treatment for yellow fever and syphilis. Both oxidation states make for nasty compounds but corrosive sublimate was by far responsible for more sickness and fatality.
Other preparations in use then (calomel was, I believe, used up until the 1950s) were metallic mercury in a finely divided state, mixed intimately with chalk, grey powder, blue pill was a similar preperation to the latter, both used again as teething powder, and for fever. Iodides, the nitrate were used and thought to stimulate the liver, particularly also to stimulate the action of the bile duct/gall bladder.
Ointments of the red oxide used to be used for styes, and inflamed eyelides (I forget which compound the red oxide, as the term was used at the time of the source for this info is, most of the names for these preparations are antiquated, and ointments of the nitrate, and oleate were used for disinfecting infected or slow healing ulcers and other sores.
To quote, 'many persons are more liable to the actions of mercury than others, even a single grain (60mg) of calomel has been known to produce in an adult all the marked symptoms connected with the mouth. Persons cannot therefore be too careful in dosing themselves with mercurials'
Referring to some initial signs of Hg toxicity, including excessive salivation and swelling of the salivary glands, or mercurial ptyalism, apparently it was known to cause, in severe cases, necrosis of the jawbone, which reminds me of the toxic effect of white phosphorus, paticularly nasty for inducing jaw necrosis, and massive, purulent abscesses, in some cases completely destroying the jaw.
Source for the above three paragraphs: The Household Physician, by J.Mcgregor Robertson, volume II, date published, 1890.
Salts of Hg tend to produce mainly peripheral symptoms, including the above, G.I tract irritation, general physical muscular weakness, joint pains and heart trouble, due to limited BBB penetration. Organomercury compounds are the devil incarnate, highly lipophilic, and penetrate the skin in seconds to minutes, the alkylmercury compounds are some of the worst, and one of the relatively few things that I refuse to work with absolutely, for any reason, such as nickel carbonyl, F2, most organic peroxides, and the likes of nasty unstable stuff that would like nothing better than to explode and take off one's face.
Dimethyl mercury for example, is about the worst thing that can come of mercury, or for that matter, anything else, volatile liquid, goes straight through latex, butyl rubber, nitrile gloves, it apparently smells, faintly, but that is no good as a warning, save to warn 'you just died horribly several months down the line' due to the low lethal dosage. To handle it, and most organizations now forbid its use completely, sealed vials and syringes are used, in combination with a full face shield, an outer layer of a special glove with an internal metal lining, and arm-length pair of inner gloves.
There was a case of a researcher using it, I think as an internal standard for NMR analysis of Hg, who spilled perhaps a hundred microliters on her latex gloves, and rapidly took them off, wikipedia states she reported removing the gloves in as little as 15 seconds. A couple of months later neurological symptoms were notices, ataxia, difficulty speaking etc, six months post exposure, despite going all out to remove the mercury via chelation, she went into a coma and died.
So clearly, the toxicity of mercury is highly dependent upon the form it takes, as does the dose taken, route and duration of exposure. AlkylHg compounds, are ones to avoid completely, one fuckup and you are ankle deep in shite from the neck up.
Interestingly, ethylmercury does not appear to show the same degree of lethality as Me2Hg, although it is still a most obnoxious compound. And what is particularly shocking really, is that it hasn't been completely banned from use in medicine, it is a metabolite of thiomersal, a preservative/adjuvant used in some vaccines. Imfamously blamed for causing autism by an wanker by the name of andrew wakefield, an A+-grade son of a syphilitic gutterslut, who was later forced to retract his paper, after he was shown to have fraudulently published false reports, and worse pulled off some sickening shit on some of our young ones including colonoscopy and even spinal taps, not to help support our health mind you, but solely to back up his bullshit 'research' data.
Guy sued a reporter who investigated him and made some claims about his being full of shit, tried to cover up his crimes, and was eventually convicted of multiple counts of child abuse and dishonesty, as well as being found to have been paid to spit up a report finding a link between autism and ethylmercury/thiomersal, and struck off the register.
Not good enough for me, personally I think the bastard should be jailed, for a long time. Abusing special needs kids deserves a good arseraping by big black, HIV+ bubba in the showers for a few decades.
After that, he slithered off with his tail between his legs to crawl over to the US, where autism awareness and rights are primitive, compared to the UK to brown-nose an child abuse promoting ex-playboy slag and extreme porn actor by the name of jenny mc'carthy, partner of a nasty organisation called 'talk about curing autism' and spokeswhore for another such organisation, generation rescue.
thats probely why i didnt find it, and my hive archive its from exact 2001-2004 ... now im missing first and BEST part. 
i mean 