Product Instructions:1. Checking the Property of the Solution: please take a small piece of test paper on the surface of the glass or vessel, use the glass rod or plastic dripper with stain to point in the middle of the test paper, observe the color changes and compare it with the color card, and determine the property of the solution.2. Check the Property of the Gas: firstly please wet the test paper with distilled water, stick it to one end of the glass rod, close the paper by glass rod to the gas, observe the color changes, and determine the property of the gas.Attention:(1) The test paper can not be directly dipped into the solution.(2) The test paper can not touch the test tube mouth, bottle mouth, catheter mouth and so on.(3) When you are measuring the pH of the solution, the test paper can not be previously wetted with distilled water, because the wetting test paper is equivalent to diluting the test solution, which can lead to inaccurate measurement. The correct way is to dip in the middle of the test paper by glass rod with solution to be tested. After the test papers; discoloration, then you can compared it with the standard color card to determine the pH of the solution.(4) After taking out the test paper, the lid of the container which contains the test paper should be tightened to avoid contamination by some gas in the laboratory.Product Parameters:1. Thickness: of Each One: about 0.2 mm / 0.01 inches2. Note: 80 pcs / book with color card3. Material: paperPackage included:1*set Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.