Limestone is by definition a rock that contains at least 50% calcium carbonate in the form of calcite by weight. All limestones contain at least a few percent other materials. These can be small particles of quartz, feldspar, clay minerals, pyrite, siderite and other minerals.
Answers (4) You have not mentioned the name of the medicine in your post. Ideally 4 times a day means every 6 hours. It depends on what the medicine is as to how rigid you should be in regards to dosing. If the medicine is an antibiotic then every 6 hour dosing is important as is pain relief medication if in severe pain. If the dosing isn't so critical then 4 times a day could be evenly spaced out during the waking hours.
With some you have to take a hormonal pill every day. With others you take a hormonal pill every day for 21 or 24 or even 26 days of the cycle, and then have a hormone free break of seven or four or only two days where either no pills are taken or a hormone free pill is taken.