No. There are several methods of canning that were employed by older generations. The open kettle method requires packing the jars with hot food or pouring boiling water over the top, then adding a lid and ring. The heat from the contents can create a seal. Another technique I've heard is to turn the jars upside down for several hours, which can also create a seal. However, a seal alone is not enough to prevent food spoilage. There is still bacteria trapped inside the jar. The only way to kill the bacteria is to heat the contents of the jar to 250 degrees F for several minutes. Also, do not try to use a microwave or an oven to process jars. Glass canning jars are not designed to be used in this way and can explode. Do not set jars out in the sun, use the heat from a dishwasher or a slow cooker. Water bath canning and pressure canning are the only two approved methods for preserving food in jars.